Most mondern OS distributions include some form of binary package management. Early package managers were little more than bundles of files that could be unpacked (such as tar or cpio archives). Over time package management has become more sophisticated and incorporated more advanced features for software management. Features common to advanced package mangers are:
The two most common package management formats are Red Hat's RPM (also used in Fedora, SuSe, and Mandriva) and the Debian DEB format (used in Debian, Ubuntu, and other distributions derived from them).
The lowest-level package management tools rpm and dpkg are rather basic. They can do simple package installation and removal and check dependencies, but won't do full dependency tracking; if you request the installation of a package with unsatisified dependencies you'll be told about direct dependencies for that package, but not the full tree of dependencies. For that reason higher-level package tools now exist such as yum on many RPM-based systems, or apt on DEB-based systems, which can do full dependency analysis for package installation and removal, as well as automating the processes of updating package availability information and downloading and installing new or updated packages.