Homebrew describes itself, on its own home page, as “The Missing Package Manager for macOS (or Linux).” It was created by Max Howell starting in 2009 to make installing open-source command-line software on the Mac as simple as a single command, filling a gap that macOS itself left open. Where a Linux distribution shipped with apt or yum, the Mac had no comparable first-party tool.
The project is built around “formulae” — small Ruby files that describe how to download, build, and install a piece of software. Because the formulae are plain Ruby scripts in a public repository, contributors could add and update packages easily, and the catalog grew quickly into one of the largest software collections on macOS.
Homebrew installs software into its own directory tree (the “Cellar”) and links it into place, keeping its packages separate from the files the operating system manages. The documentation notes that on Linux “Homebrew does not use any libraries provided by your host system, except glibc and gcc if they are new enough,” making installations relatively self-contained.
Originally a Mac-only tool, Homebrew later expanded to Linux and Windows Subsystem for Linux. The project’s documentation states that “Homebrew was formerly referred to as Linuxbrew when running on Linux or WSL,” and now lets users “use the same package manager to manage your macOS, Linux, and Windows systems.”