What does 'ELI5' mean on Reddit?

“What does ‘ELI5’ mean on Reddit?” — “Explain like I’m 5.” It is a request for a clear, beginner-friendly explanation of a complicated subject, using little jargon and assuming the reader has no specialist background.

ELI5 is closely associated with Reddit’s r/explainlikeimfive community, which was created in January 2011. The subreddit invites questions about science, technology, history, economics, and other topics, then encourages knowledgeable users to explain them in accessible language. The phrase is figurative: it generally means “explain this simply,” not “speak to me as though I am literally five years old.”

A common misunderstanding is that an ELI5 answer must be extremely short or childish. Good explanations can still include accurate technical detail; they simply introduce ideas step by step and define unfamiliar terms. The phrase has also spread beyond Reddit into journalism, classrooms, software documentation, and everyday online conversation. “Explain like I’m five” and “explain like I’m 5” express the same meaning; the numeral is just the customary internet shorthand.