Biologically, a child (plural: children) is generally a human between the stages of birth and puberty. Some definitions include the unborn (termed fetus). The legal definition of "child" generally refers to a minor, otherwise known as a person younger than the age of majority. "Child" may also describe a relationship with a parent or authority figure, or signify group membership in a clan, tribe, or religion; it can also signify being strongly affected by a specific time, place, or circumstance, as in "a child of nature" or "a child of the Sixties."

The following outline is provided as an overview of and topical guide to children:

Lilian Katz is a Professor Emerita of early childhood education at the University of Illinois at Urbana-Champaign, where she is also principal investigator for the Illinois Early Learning Project, a contributor to the Early Childhood and Parenting Collaborative, and editor of the first on-line peer-reviewed early-childhood journal, Early Childhood Research & Practice. She was born and raised in England and received her Ph.D. in Child Development from Stanford University in 1968.

Katz is a past president of the National Association for the Education of Young Children and former Director of the ERIC Clearinghouse on Elementary & Early Childhood Education. She has published Talks with Teachers of Young Children (1995), a collection of her essays. In 2001 the second edition of her Engaging Children's Minds: The Project Approach (with S. C. Chard) was published. For thirteen years, she wrote a monthly column for Parents Magazine. Katz was founding editor of the Early Childhood Research Quarterly, and served as editor-in-chief during its first six years. She is currently chair of the editorial board of the International Journal of the Early Years published in the United Kingdom. The Clearinghouse on Early Education and Parenting (CEEP) organized a symposium in her honor in 2000.