In software engineering, a modular and replaceable part of a system that encapsulates its contents and whose manifestation is replaceable within its environment.

"React components allow developers to split the UI into independent, reusable pieces to handle each piece separately."

Independent and reusable bits of code that work in isolation and return HTML via a render function.

"React components let you split the UI into independent, reusable pieces to handle each part of the interface separately."