Yellowdog Update, Modified (YUM) is a package manager that was developed by Duke University to improve the installation of RPMs. yum searches numerous repositories for packages and their dependencies so they may be installed together in an effort to alleviate dependency issues. Red Hat Enterprise Linux 5.2 uses yum to fetch packages and install RPMs.

up2date is now deprecated in favor of yum (Yellowdog Updater Modified). The entire stack of tools which installs and updates software in Red Hat Enterprise Linux 5.2 is now based on yum. This includes everything, from the initial installation via Anaconda to host software management tools like pirut.

yum also allows system administrators to configure a local (i.e. available over a local network) repository to supplement packages provided by Red Hat. This is useful for user groups that use applications and packages that are not officially supported by Red Hat.

Aside from being able to supplement available packages for local users, using a local yum repository also saves bandwidth for the entire network. Further, clients that use local yum repositories do not need to be registered individually to install or update the latest packages from Red Hat Network.