In medicine and the social sciences, a young adult is generally a person in the years following adolescence, sometimes with some overlap. Definitions and opinions on what qualifies as a young adult vary, with works such as Erik Erikson's stages of human development significantly influencing the definition of the term; generally, the term is often used to refer to adults in approximately the age range of 18 to 45 years. Some inclusive definitions extend the range into the early to mid 40s, while others end earlier.
The United States Census Bureau, for instance, defines young adults as those between the ages of 18 and 34. Over 65 million Americans born approximately from 1990 to 2006, would likely fall under this category. The young adult stage in human development precedes middle adulthood.