Code base

In software development, a codebase (or code base) refers to a whole collection of source code that is used to build a particular software system, application, or software component. Typically, a codebase includes only human-written source code files; thus, a codebase usually does not include source code files generated by tools (generated files) or binary library files (object files), as they can be built from the human-written source code. However, it generally does include configuration and property files, as they are the data necessary for the build.

A codebase is typically stored in a source control repository that belongs to a revision control system. For smaller projects it may be kept as a simple set of files (even the Linux kernel was maintained as a set of files for many years). A source code repository is a place where large amounts of source code are kept, either publicly or privately. Source code repositories are used most basically for backups and versioning, and on multi-developer projects to handle various source code versions and to provide aid in resolving conflicts that arise from developers submitting overlapping modifications. Subversion, Git and Mercurial are examples of popular tools used to handle this workflow, which are common in open source projects.

Multiple projects can have separate, distinct codebases, or can have a single, shared or monolithic codebase. This is particularly the case for related projects, such as those developed within the same company. In more detail, a monolithic codebase typically entails a single repository (all the code in one place), and often a common build system or common libraries. Whether the codebase is shared or split does not depend on the system architecture and actual build results; thus, a monolithic codebase, which is related to the actual development, does not entail a monolithic system, which is related to software architecture or a single monolithic binary. As a result, a monolithic codebase may and (for large codebases) often will consist of separate components, instead of carrying only a single system or single binary; a distributed codebase (with multiple components) can be used to build a single monolithic system or even a single binary. For example, the Linux kernel is architecturally a single monolithic kernel, but it consists of separate binaries (loadable components), and is developed in multiple distributed repositories.

...
Wikipedia