February 2020 Issue

Picky Eating in Children — A Comprehensive Review
By Rivanna Stuhler, MSc, RD
Today’s Dietitian
Vol. 22, No. 2, P. 40

Picky eating is a common problem of childhood. It’s often considered fairly trivial and transient in nature, but in some cases it may lead to inadequate weight gain, nutrient deficiencies, and long-lasting behavioral issues that can be difficult to change. For some children, “picky eating” is a sign of a much more serious issue that requires medical intervention and referral to specialist services.

Changing food-related behavioral issues that are well entrenched is extremely challenging for parents and dietitians alike and requires patience and a great deal of support for the family and child. Families are more likely to see success if picky eating behaviors are recognized and addressed early, but if parents’ and caregivers’ concerns are dismissed, as routinely happens, success is less likely to occur. For dietitians, a comprehensive understanding of picky eating is vital to successfully provide care and create effective nutrition care plans.

This article discusses parents’ perceptions and behaviors associated with picky eating, explains normal feeding development identification and management of picky eating and feeding disorders in general, and offers practical strategies for managing picky eating behaviors.

Parents’ Perceptions and Behaviors
A study by Byrne and colleagues that examined maternal perceptions of fussy eating in their children found that approximately 30% of mothers characterize their children as picky or fussy eaters,1 a proportion supported by Brown and colleagues and Mascola and colleagues.2,3 The perception of a child as a picky eater is highest among mothers of children with a lower weight status or BMI percentile.4 The most commonly reported signs of picky eating in children by parents or caregivers are food neophobia, parents’ perception of a limited diet, noted decreased enjoyment of food, rigid or limited behaviors related to food/eating, and slow eating.5 Parents and caregivers of picky eaters self-identify as those who put more pressure on a child to eat, such as to control the level of intake vs responding to the child’s natural hunger/satiety cues; use bribery as a way of getting their child to eat; and are more likely to be picky eaters themselves.2,6-8 These parental behaviors and tendencies are replicated in many similar studies and reviews.1,9-13 In addition, mothers who admit to using pressuring techniques are more likely to identify their children as picky eaters. Lumeng and colleagues found an association between pressuring behaviors and picky eating, but no association with poor growth.13 Brown and colleagues report the same finding.2 Byrne and colleagues note variability in perception among parents and caregivers and assert that studies rarely look at actual intake but instead focus on parental perception.1 Thus, it’s difficult to quantify how many of the 30% of perceived picky eaters are at risk of failure to thrive, require further medical investigation for organic causes of picky eating, or need complex medical intervention. Therefore, it’s imperative for dietitians to have a thorough understanding of normal feeding development and the commonly seen issues related to picky eating.

Normal Development of Eating From Infancy Through Childhood
Normal eating is the ability to recognize hunger and then eat enough to satiate oneself—recognizing a feeling of fullness. It also encompasses the ability to choose foods one likes and enjoy those foods without an extreme restriction placed on the amount eaten.14,15 Included is the ability to eat for pleasure or for comfort in amounts that aren’t excessive. In her book How to Get Your Kid to Eat … But Not Too Much, Ellyn Satter, MS, RD, states, “Normal eating is flexible. It varies in response to your emotions, your schedule, your hunger, and your proximity to food.”14 While normal eating varies from person to person—some people eat small, more frequent meals vs three large meals; prefer to snack or not; and differ in how emotionally stimulated/comforted they are by food—it generally encompasses a healthy attitude toward food. Healthy infants and children are born with an innate capacity to eat normally, one that changes based on their experiences and exposure to food.14-16

Normal Feeding Development From Infancy Into Adolescence

Between birth and 4 to 5 months, sucking from the breast or bottle is how infants receive nutrition. They become more adept at feeding as they grow bigger and stronger and can take in larger volumes more quickly. At around 4 to 6 months of age, they’re able to hold up their torsos and heads and have the oro-motor skills to accept food from a spoon.17 Many enjoy the tactile nature of playing with food and will have no problems getting their hands and faces dirty.14,16,17 They begin to develop a capacity to manage new textures and their chewing skills. Gagging on new textures is extremely common and considered normal as the infant learns new skills related to eating.14-17 However, many parents become quite alarmed when their children gag, as they can’t tell the difference between gagging (normal) and choking (abnormal). If parents or caregivers react strongly each time this happens, children may become less willing to try new textures, as they may be frightened by the reaction of their parents/caregivers.14

As infants approach 1 year of age, they begin to assert their independence. This may present as a reluctance to be spoon fed. However, if given the spoon, these infants may be happy to feed themselves (albeit clumsily), and they’re more willing to feed themselves when presented with finger foods and small, easy-to-manage solids, such as well-cooked pieces of pasta or vegetables, cut fruit, small pieces of cheese, or small pieces of bread with a spread.14,15,17,18

Toddlers are curious explorers, learning to become more autonomous and independent and navigate the world. They have a greater sense of themselves as individuals and like to express it.1,14,15,19 They try to push boundaries, but at the same time appreciate limits, as these provide structure and a sense of safety. They become more skilled at feeding themselves and are capable of progressing to a modified adult diet devoid of choking hazards such as whole nuts, as they don’t have the skills to safely expel these foods.17 Although their skill sets are expanding, they experience neophobia and so may not be willing to try or accept new foods.14-16,18 Because growth rates and appetites naturally decrease after 1 year of age, their appetites fluctuate day to day and sometimes even meal to meal.1,4,17

Preschool Age
As children reach preschool and school age, neophobia begins to decrease and in most cases disappears almost entirely.14,15,18 Children of this age have more advanced chewing and swallowing skills and become more adept at using cutlery.17 They’re more coordinated when eating and drinking and may spill less or be more efficient eaters and drinkers in general. Their appetite continues to be variable, as with toddlers, but they’re much more aware of the feeding environment and easily influenced by food-related attitudes around them or the environment in which they eat (eg, if the house is noisy or chaotic, or there’s tension or discord between parents/guardians or family members).14-18

School Age
At this age, children have all of the developmental skills required for eating and can tolerate a regular adult diet. As they may eat one or more meals out of the house each day, they have more freedom regarding what they choose to eat. They have a basic understanding of nutrition and can help with meal planning and preparation.14,15,18 They’re heavily influenced by their peers and environment and look to their parents and caregivers to be good role models in relation to attitudes toward food and eating in general.18

Adolescents have much more freedom in terms of eating and drinking. They may have disposable income, which they can spend on snacks or meals while hanging out with friends. They still appreciate having meals provided for them, as they see this as a sign of caring.14 Adolescence is a period of great influence, and this is the time when odd eating behaviors or perhaps even signs of eating disorders appear (although some children exhibit signs of eating disorders well before adolescence).14,15,17 While teenagers should have freedom around nutrition, parents or caregivers still may provide guidance and be aware of any alarming behaviors or changes in eating habits.

Roles of Parents and Children
The golden rule when considering who’s responsible for what when feeding children is as follows: “Parents are responsible for what is presented to eat and the manner in which it is presented. Children are responsible for how much they eat, and even whether they eat.”14 The child’s role in the feeding relationship remains fairly static from infanthood to adolescence, while the parents’ or caregivers’ role changes to match the developmental stage of the child.

In the newborn stage, infants are learning about the world and their direct caregivers and developing trust. Their primary objective is to have their needs met. The parents’ or caregivers’ role is to meet the needs of young infants by learning their cues and responding to them.9,14,15 This includes feeding infants when they’re hungry but respecting cues that they’re full and not pushing the breast or bottle.12,14 This can be difficult for parents who bottle-feed their infants and feel they have to feed a specific volume of formula on a schedule, as the intake of infants may vary slightly.

In later infancy (roughly 5 to 12 months of age), the parent’s role is to select the food to offer and progress through textures based on the cues and capacity of the child. Some children may progress to soft solids very quickly, preferring them to puréed foods; others may be a bit more cautious and require more patience and time. If infants trust their food providers, they will be more willing to try new foods or textures.12 The parent’s or caregiver’s understanding of the difference between gagging and choking and responding appropriately also can help foster a safe, trusting environment in which the infant can develop new feeding skills.16,17 Allowing infants to play with food and get messy can be very helpful for feeding development, as the tactile nature of this activity can help them develop a positive attitude toward food.12,17

Toddlers, as they become more autonomous, push boundaries. This is a normal part of development but shouldn’t be indulged. Instead, the role of parents or caregivers is to create a structured schedule, routine, and environment for meals and snacks, which should be followed as closely as possible.14,15 Parents or caregivers continue to choose the foods to be provided, and the toddler decides whether and how much to eat.14-16 As appetite and intake vary widely during this period of development, the toddler’s choices should be respected unless there are concerning signs noted, including suboptimal weight gain.

As mentioned previously, preschool and school-age children are much more independent and involved in deciding when and whether to eat and may eat out of the house more, particularly with friends.14,15 They should be encouraged to try new foods and explore different cuisines. Whenever possible, fights at the table about eating should be avoided.14-17 At the same time, parents or caregivers should continue to offer consistent and healthful meals, and, sometimes, snacks. The older the children, the more capable they are of choosing and preparing snacks and even getting involved in meal planning and preparation. The role of parents or caregivers remains the same for adolescents, who are almost completely independent when it comes to snack choices and even preparation of some meals.

Understanding the developmental stages children go through in relation to food and eating is important for parents and dietitians, as they easily can pick up on red flags that may indicate an emerging feeding disorder.

Identifying Feeding Disorders: Red Flags
Feeding disorders often have many causes, some of which may be related. Causes may be organic, environmental, or behavioral in nature, or a combination of all three factors.20 Regardless of the cause, parents and caregivers who voice concerns about their children’s feeding behaviors should never be ignored, as these concerns may turn in to a serious condition requiring medical intervention.6 It’s important to conduct a thorough feeding and behavioral history and take anthropometric measures, and a physical examination may be necessary to help determine the source of the issue. Even when the problem turns out to be minimal and easily addressed with education or suggestions for behavioral interventions, dietitians should provide constructive and practical recommendations to parents and caregivers.9 Some of these recommendations may include a shift in the feeding style of the parents, encouraging them to look for and react to their child’s hunger and satiety cues, or a change made to the feeding environment, such as the removal of distractions. Examples of some common suggested changes can be found in the “Practical Tips for Dietitians” section.

Organic causes of feeding disorders include anatomical defects, gastrointestinal (GI) diseases or disorders, and genetic syndromes.9 These may affect children’s desire to eat as well as their mechanical ability to eat or drink. In these cases, developmental readiness, including children’s ability to hold their trunks and heads up, or the ability to chew and swallow safely, also may need to be considered. Anatomical defects such as cleft palate, abnormal facial structure, or laryngomalacia may compromise a child’s capacity to eat or drink normally.20 Children with hyper- or hypotonicity may be at increased risk of reflux, dysphagia, or aspiration and should be carefully assessed for feeding safety. Children with disturbances of the GI tract such as gastroesophageal reflux disease, food allergies, eosinophilic esophagitis, or celiac disease may present with food-averse or -avoidant behaviors.9,20 Children with various genetic diseases such as trisomy 21 (ie, Down syndrome) may be at heightened risk of feeding disorders due to the nature of their diagnoses.6,20 These children should be monitored carefully.

Environmental factors that may lead to feeding disorders include the home or school environment where the majority of meals and the relationship between the child and the adult feeding them (eg, parent, caregiver, teacher) take place.20 In addition, socioeconomic factors such as income and education levels (of the parents/caregivers) and access to food (ie, food security) may affect the feeding environment. A thorough history includes a diet history but also an environmental scan related to meals and feeding practices. This should include questions about where meals take place (eg, at the table? In front of a screen?), how calm or chaotic the feeding environment is, and any alarming behaviors, such as force-feeding, that may be reported by the parents (see table).

Behavioral issues (as outlined in the table) may manifest as a result of undiagnosed organic factors, environmental factors that haven’t been addressed, or, in some cases, traumatic experiences from the past (eg, intubation, chemotherapy, resolved GI pathology). Dietitians should be aware that although behavioral issues are modifiable, some children who exhibit continued behaviors before and after intervention are at risk of poor growth, failure to thrive, and nutrient deficiencies.3,4,11 Ignoring the behaviors reported by caregivers can lead to a long-lasting unhealthy relationship with food and can be extremely stressful for families and clinicians.6 Indeed, children whose picky eating behaviors persist longer than about two years may benefit from additional attention from dietitians and other clinicians to determine the best course of action, whether it be ongoing support for caregivers, referral to a specialist team, or referral to a clinician who provides psychological support.3 Children who exhibit behaviors related to feeding without any medical cause respond best to early intervention and suggestions for behavior modification (both for the child and the parent/caregiver), as outlined in the section “Practical Tips for Dietitians.” In more difficult cases, referral to a specialist feeding team may be required.9,20

The following table lists some of the more common red flags that may indicate a feeding disorder or other picky eating behavior. As some reported signs overlap, further questioning is required to determine the actual cause of the behavior. For example, is the parent overly anxious about choking or unaware of the difference between normal gagging vs choking and so doesn’t offer the child appropriate textures (environmental red flag)? Or is the child refusing to try new textures even with repeated attempts (organic or behavioral red flag)?

Click to enlarge

Common Themes Seen in Children With Feeding Issues

Children With Limited Appetite
Children with limited appetite present along a spectrum, from those with obvious organic disease leading to suboptimal intake or noted decreased appetite, to those who eat an appropriate amount and are growing well but who are misperceived by parents and/or caregivers to eat too little. This misperception about toddlers is extremely common, given that toddlers are busy and some days may appear to eat little, which causes considerable worry to parents. Helping parents and caregivers understand that their children are growing appropriately and taking in enough despite the perception that they aren’t is vital to maintaining a healthy eating environment.9 A comprehensive diet history is an important component of assessing children with reported limited appetite to determine whether a problem truly exists.

Children With Food-Related Selectivity
A wide spectrum of food-related selectivity is commonly seen in children. Understanding neophobia and being able to differentiate between normal age-related selectivity and truly restrictive behaviors that warrant further medical or psychological assessment is important for dietitians.6 A child’s ability to safely bite, chew, or swallow a food may present as a preference for certain textures and tastes (eg, preferring thicker fluids such as yogurt but refusing to drink water or juice because it’s thinner and harder to swallow). This is extremely common in children with organic disease but also may be seen in children with oral hypo- or hypersensitivity, such as those with an inability to taste mild flavors or enjoy softer textures (ie, oral hyposensitivity), or those who find flavor and texture—of almost any kind, depending on the child—overwhelming (ie, oral hypersensitivity).6,12 Parents of picky eaters often report that their children have extreme hypersensitivity to food textures and tastes and a negative association with food and eating as a result.5,6 As such, asking parents and caregivers careful questions can help dietitians best understand the situation and determine a plan of care. Appropriate questions include “Will your child only eat strongly flavored foods?” to ascertain whether hyposensitivity exists, and “Does your child cough, choke, or sputter with water or juice?” to help understand a child’s capacity to swallow safely.9,11

Children With a Fear of Food
Some children experience true fear or anxiety related to food. For some, this is as a result of a traumatic experience, such as being fed while suffering from untreated GERD (which causes extreme pain or discomfort, leading to a negative association with food or eating), a traumatic or prolonged intubation leading to oral aversion, or undiagnosed dysphagia (commonly seen in children diagnosed with eosinophilic esophagitis). Other children develop food-related fear or anxiety after being repeatedly force-fed by parents or caregivers.9,14,15 Medical or behavioral management can be helpful in reducing anxiety over time, but progress may be slow and requires a great deal of patience from parents and clinicians alike.

Strategies for Managing Picky Eaters
Many dietitians who work with young children and their families know that behavioral management of picky eaters is a long and arduous process. As well as providing direction and helpful strategies, dietitians need to support those providing the food. This may include setting realistic expectations for change (eg, telling caregivers, “This may take a few weeks”); acknowledging that parents and caregivers may feel guilt or feel they’re starving their children, even though this isn’t true; and letting parents and caregivers know they should expect pushback from their children. Reminding parents to be patient is vital to the success of behavioral management strategies. Coaching parents and caregivers to create healthy feeding environments is a necessary part of any behavioral intervention, as the parents’ or caregivers’ feeding styles (eg, controlling feeders who ignore the children’s hunger/satiety cues, indulgent feeders who give in to the children, or neglectful feeders who don’t provide adequate food or attention) may be a contributing factor to their children’s behavior.9

Considerations for Further Medical Intervention
Children who are known to have mechanical difficulty with food should be referred to a specialist feeding team, an occupational therapist, or a speech pathologist for assessment of skills and recommendations for safe feeding. These children may require altered textures, specialized seating (eg, modified or customized wheelchairs, high chairs, or standard seating) or utensils, medication, or aids such as g-tubes to safely feed.9,20 Children with extreme selective eating, developmental delay, or who are thought to have autism spectrum disorder may benefit from a referral to a developmental pediatrician, who can best assess the needs of the child and refer to specialist services.

Practical Tips for Dietitians
Due to the variety of complex circumstances under which picky eating may occur, dietitians should aim to provide tailored advice for each case of picky eating. General guidelines exist, but they may not always work for everyone. Parents and caregivers will respond to suggestions they feel are practical, realistic, achievable, and relevant to their children. Creating a sympathetic and respectful rapport with parents and caregivers can foster trust, which will only serve to help dietitians. Parents and caregivers who feel respected and heard are more likely to be open to suggestions. Asking questions in a sensitive manner and reframing or restating these questions if necessary to get the required information can help dietitians adapt their therapeutic approach to achieve success. To do this, dietitians must pay close attention to the history and the “story” the parents and caregivers tell, as well as their body language. These are all excellent clues to help guide an impression and plan.

Regardless of their impression, dietitians must remember that providing parents and caregivers with several recommendations at one time can be overwhelming and may not be practical. Multiple consults may be required to gradually change the behavior of children (and/or that of their caregivers).

Picky eating is a complex part of childhood. It may be mild and easily resolved or a more challenging behavioral or medical issue that requires specialist intervention. Dietitians should be aware of the intricacy of this issue so they can advise parents and caregivers and provide the best possible care to their children.

— Rivanna Stuhler, MSc, RD, is a Toronto-based acute-care pediatric and private practice dietitian. Stuhler currently specializes in pediatric blood and stem cell transplant and works in private practice with children and adults. Her graduate work focused on quality improvement and patient safety in health care.


1. Byrne R, Jansen E, Daniels L. Perceived fussy eating in Australian children at 14 months of age and subsequent use of maternal feeding practices at 2 years. Int J Behav Nutr Phys Act. 2017;14(1):123.

2. Brown CL, Vander Schaaf EB, Cohen GM, Irby MB, Skelton JA. Association of picky eating and food neophobia with weight: a systematic review. Child Obes. 2016;12(4):247-262.

3. Mascola AJ, Bryson SW, Agras WS. Picky eating during childhood: a longitudinal study to age 11 years. Eat Behav. 2010;11(4):253-257.

4. Ekstein S, Laniado D, Glick B. Does picky eating affect weight-for-length measurements in young children? Clin Pediatr. 2010;49(3):217-220.

5. Boquin M, Moskowitz HR, Donovan SM, Lee S. Defining perceptions of picky eating obtained through focus groups and conjoint analysis. J Sens Stud. 2014;29(2):126-138.

6. Cardona Cano S, Hoek HW, Bryant-Waugh R. Picky eating: the current state of research. Curr Opin Psychiatry. 2015;28(6):448-454.

7. Brown CL, Pesch MH, Perrin EM, et al. Maternal concern for child undereating. Acad Pediatr. 2016;16(8):777-782.

8. Elkins A, Zickgraf HF. Picky eating and food neophobia: resemblance and agreement in parent/young adult dyads. Appetite. 2018;126:36-42.

9. Kerzner B, Milano K, MacLean WC Jr, Berall G, Stuart S, Chatoor I. A practical approach to classifying and managing feeding difficulties. Pediatrics. 2015;135(2):344-353.

10. Taylor CM, Wernimont SM, Northstone K, Emmett PM. Picky/fussy eating in children: review of definitions, assessment, prevalence and dietary intakes. Appetite. 2015;95:349-359.

11. Green RJ, Samy G, Miqdady MS, et al. How to improve eating behaviour during early childhood. Pediatr Gastroenterol Hepatol Nutr. 2015;18(1):1-9.

12. Dovey TM, Staples PA, Gibson FL, Halford JC. Food neophobia and “picky/fussy” eating in children: a review. Appetite. 2008;50(2-3):181-193.

13. Lumeng JC, Miller AL, Appugliese D, Rosenblum K, Kaciroti N. Picky eating, pressuring feeding, and growth in toddlers. Appetite. 2018;123:299-305.

14. Satter E. How to Get Your Kid to Eat … But Not Too Much. Boulder, CO: Bull Publishing Company; 1987.

15. Rowell K, McGlothlin J. Helping Your Child With Extreme Picky Eating: A Step-By-Step Guide for Overcoming Selective Eating, Food Aversion, and Feeding Disorders. Oakland, CA: New Harbinger Publications: 2015.

16. Satter EM. The feeding relationship. J Am Diet Assoc. 1986;86(3):352-356.

17. Worthington-Roberts BS, Rodwell Williams S. Nutrition Throughout the Life Cycle. 4th ed. Boston, MA: McGraw-Hill; 2000.

18. Durea TK. Dietary recommendations for toddlers, preschool, and school-age children. UpToDate website. https://www.uptodate.com/contents/dietary-recommendations-for-toddlers-preschool-and-school-age-children. Updated December 16, 2019.

19. Chong Cole N, An R, Lee S, Donovan SM. Correlates of picky eating and food neophobia in young children: a systematic review and meta-analysis. Nutr Rev. 2017;75(7):516-532.

20. Nieman Carney L, Nepa A, Shubin Cohen S, Dean A, Yanni C, Markowitz G. Parenteral and enteral nutrition support: determining the best way to feed. In: Corkins MR, ed. The ASPEN Pediatric Nutrition Support Core Curriculum. 1st ed. Silver Spring, MD: American Society for Parenteral and Enteral Nutrition; 2010:433-447.


• Set structured schedules with meals and snacks provided at approximately the same time each day.

• Encourage a safe and welcoming feeding environment. Meals should be eaten at the table without distractions such as books, toys, or screens (televisions, tablets, etc).

• Parents and caregivers should be encouraged to sit with their children during meals.

• Eating as a family should be encouraged.

• Keep mealtimes to a maximum of 20 to 30 minutes, as children have short attention spans. The younger the child, the shorter the meal (15 to 20 minutes for toddlers, 20 to 30 minutes for older children).

• Alternative meals shouldn’t be provided to the child who refuses the meal the rest of the family is eating. Parents and caregivers should be reminded that they’re not short-order cooks and aren’t responsible for cooking a separate meal for each family member.

• If the child refuses to eat the meal provided, no food or drink other than water should be given until the next scheduled meal/snack. If this behavior continues for more than one to two weeks, parents should consider speaking with their medical team about strategies to improve intake.

• Children shouldn’t be given snacks or large drinks less than one hour before meals, as this may blunt hunger and affect intake.

• Encourage children to eat solids first and drink at the end of a meal, as they may eat more if not full from liquids.

• Parents and caregivers should be encouraged to avoid nagging, yelling, or coercing their children to eat.

• Avoid threats related to food intake.

• Praise positive behaviors and ignore negative behaviors entirely. Children who see that a certain behavior elicits no response often stop the behavior in time.

• All caregivers should agree to use the same strategies so that the children experience a consistent approach.

• Continue to offer foods the children won’t eat in small amounts at each meal, even if they continue to refuse. Children may require exposure to a food 15 to 20 times before they will try or accept it. Withdrawing these foods doesn’t enable children to explore at their own pace.

• Continue to introduce new foods. Some children respond well if an adult tries the food at the same time they do.

• Provide foods that are developmentally appropriate for the child. Don’t shy away from flavorful foods, as many children who are picky prefer these.

• Encourage food play and food exploration, particularly with new foods or textures. Don’t be afraid to let the child get messy—the tactile experience with food is a healthy developmental part of eating.

• A reward system that doesn’t involve food or material goods may be helpful for children older than 1 year (eg, an extra book at story time, an extra cuddle before bed). Children respond well to additional attention and time with the adults in their lives and don’t need material goods or food as rewards.

• Remind parents and caregivers that this process requires patience and a great deal of stamina.

— RS


1. Say goodbye to picky eating! UnlockFood.ca website. http://www.unlockfood.ca/en/Articles/Child-Toddler-Nutrition/Say-Goodbye-to-Picky-Eating!.aspx. Updated May 1, 2019.

2. Dietitians of Canada. Tips on feeding your picky toddler or preschooler. https://www.dietitians.ca/Downloads/Factsheets/Tips-Feeding-Picky-Toddler.aspx. Published 2014. Accessed December 2017.

3. Motil KJ, Duryea TK. Patient education: poor weight gain in infants and children (beyond the basics). UpToDate website. https://www.uptodate.com/contents/poor-weight-gain-in-infants-and-children-beyond-the-basics. Updated January 18, 2019.