A codebase is the entire collection of source code that is used to build a software application or system. It consists of all the files, scripts, assets, and configuration settings that developers work on to develop, maintain, and improve the software. The codebase is typically stored in a version control system (VCS) like Git, which helps teams manage code changes, track modifications, and collaborate on development.

A well-organized codebase is modular, with clearly defined structures, making it easier for teams to understand and contribute to. Modular codebases promote the reuse of components, reduce redundancy, and simplify maintenance. As a project evolves, the codebase grows, and keeping it manageable requires best practices such as documentation, code reviews, and adhering to coding standards.

Having a single source of truth, a codebase ensures consistency across environments (development, testing, and production). Properly managed codebases facilitate Continuous Integration/Continuous Deployment (CI/CD), allowing for the automation of builds, testing, and deployment.

In larger organizations, the concept of a monorepo or microrepo may be used, depending on whether the codebase for multiple projects is centralized or split into smaller repositories.