macOS ships with a generous toolkit out of the box — but it stops at the doorstep of modern development. There's no git by default until you accept the Xcode Command Line Tools. There's no node, no python3.12, no postgresql, no ffmpeg, no ripgrep. There's no clean way to install Firefox or VSCode without dragging .dmg files around. Homebrew is the answer to all of that.
Homebrew (often called "brew") is a community-driven package manager for macOS and Linux that gives you a single CLI to install, update, and remove thousands of open-source tools. It manages dependencies automatically, keeps everything updated in one command, and installs into a sandboxed prefix so it never fights with macOS itself. On Apple Silicon Macs the prefix is /opt/homebrew; on older Intel Macs it's /usr/local — that path difference is the single biggest gotcha later.
Two kinds of installable things live in Homebrew: formulae (CLI tools and libraries — git, python, postgresql@16) and casks (GUI macOS apps — firefox, iterm2, visual-studio-code). Both install with the same command. The result is a Mac where almost everything you need can be expressed as text — and that's exactly what makes a Brewfile-driven setup so powerful.
Homebrew is also the gateway drug to almost every other package manager in this quest. Want node? brew install node. Want uv? brew install uv. Want miniconda? brew install --cask miniconda. Even Pippa's own backend runs on Python 3.12 from a conda env that was originally bootstrapped through Homebrew.