The Yellowdog Updater Modified (YUM) is a free and open-source command-line package-management utility for computers running the Linux operating system using the RPM Package Manager.

Under the hood, YUM depends on RPM, which is a packaging standard for digital distribution of software, which automatically uses hashes and digital signatures to verify the authorship and integrity of said software; unlike some app stores, which serve a similar function, neither YUM nor RPM provide built-in support for proprietary restrictions on copying of packages by end-users.

[12] The original package manager, Yellowdog UPdater (YUP) was developed in 1999-2001 by Dan Burcaw, Bryan Stillwell, Stephen Edie, and Troy Bengegerdes at Terra Soft Solutions (under the leadership of then CEO Goutham Krishna) as a back-end engine for a graphical installer of Yellow Dog Linux.

[4] As a full rewrite of YUP, YUM evolved primarily to update and manage Red Hat Linux systems used at the Duke University Department of Physics by Seth Vidal and Michael Stenner.

Vidal continued to contribute to YUM until his death in a Durham, North Carolina bicycle accident on 8 July 2013.

[17] YUM aimed to address both the perceived deficiencies in the old APT-RPM,[18] and restrictions of the Red Hat up2date package management tool.

[4] While yum was originally created for Linux, it has been ported to a number of other operating systems including AIX,[22] IBM i,[23] and ArcaOS.

[8] Yum Extender was deprecated for a while when Fedora migrated to DNF,[28] but it was rewritten in Python 3 and Gtk 3 and has been in progress for development.