Framework

Definitions

A framework is a reusable software platform that provides foundational structure, conventions, and built-in functionality for building applications within a specific domain. The defining characteristic is inversion of control: unlike a library (which your code calls), a framework calls your code through hooks, lifecycle methods, or configuration points you fill in. Web frameworks like Django, Rails, Express, and Spring Boot handle routing, middleware, templating, and database access. Frontend frameworks like React, Angular, and Vue manage component rendering and state. Frameworks enforce opinions about project structure, which accelerates development but can constrain flexibility. Choosing a framework is a significant decision because it shapes the codebase for the project's lifetime.
In plain English: A pre-built skeleton for your application that dictates the overall structure — you fill in the blanks, and it handles the plumbing.
Example: "A library is a tool you use. A framework is a lifestyle you adopt."