Framework
In plain terms
A reusable structure that provides scaffolding for applications.
Going deeper
A framework defines an application's architecture and calls your code at the right points (inversion of control), unlike a library you call. It shapes how you build.
Under the hood
The 'Hollywood principle' (don't call us, we'll call you) distinguishes it from libraries.
Examples
React, Django, Spring, Angular, Rails, application scaffolding.
Think of it like...
Like a building's pre-built frame you fill in, rather than loose tools you arrange yourself.