Linux distributions are normally segmented into packages. Each package contains a specific application or service. Examples of packages include a library for handling the PNG image format, a collection of fonts, or a web browser.
The package is typically provided as compiled code, with installation and removal of packages handled by a package management system (PMS) rather than a simple file archiver. Each package intended for such a PMS contains meta-information such as a package description, version, and "dependencies". The package management system can evaluate this meta-information to allow package searches, to perform an automatic upgrade to a newer version, to check that all dependencies of a package are fulfilled and/or to fulfill them automatically.