What is common?

Doctrine Common is a PHP library maintained as part of the Doctrine project, a widely used collection of open-source tools for database-related work in PHP. The project describes itself as providing extensions to core PHP functionality, but the README is extremely brief and does not explain what those extensions are, how to install the library, or how to use it. The library exists primarily as a shared dependency. Other packages in the Doctrine ecosystem, including Doctrine ORM (which maps database rows to PHP objects) and Doctrine DBAL (which provides a database abstraction layer), pull in Doctrine Common as a foundation for shared code. Developers typically encounter this package indirectly as a transitive dependency of those higher-level tools, rather than by depending on it directly in their own projects. The README provides three links: the main Doctrine website at doctrine-project.org, a dedicated documentation section for Doctrine Common, and a GitHub releases page. For anyone who needs to understand what the library actually contains, the documentation site or the source code would be more informative than the README. The project runs continuous integration and tracks code coverage, which indicates it is actively maintained. Because the README is so sparse, there is simply not much more to describe without going beyond what the source material states. If you need to use this library, the official Doctrine documentation is the right place to start.