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Mac & Homebrew Glossary

Key terms you will encounter when setting up your Mac with Homebrew. Each definition includes examples and related terms.

In-depth guides

Apple Silicon

Apple's custom ARM-based processors for Mac (M1, M2, M3, M4 series). Apple Silicon Macs use the arm64 architecture and install Homebrew to /opt/homebrew instead of /usr/local. Most modern Mac apps are now compiled natively for Apple Silicon, offering significant performance improvements over Intel versions.

Brewfile

A plain text file that lists all Homebrew packages, casks, and taps you want installed. Running "brew bundle" installs everything in the Brewfile, making it easy to reproduce your entire Mac setup on a new machine. It is the standard way to version-control your macOS development environment.

brew bundle --file=~/Brewfile

Cask

A Homebrew extension for installing macOS graphical applications (GUI apps). While Homebrew Formulae install command-line tools, Casks install desktop apps like VS Code, Arc, Figma, and Slack by downloading and moving them to the Applications folder automatically.

brew install --cask visual-studio-code

Cellar

The directory where Homebrew installs formula packages. On Apple Silicon Macs, this is /opt/homebrew/Cellar. Each installed formula gets its own subdirectory with version-specific folders, allowing multiple versions to coexist.

/opt/homebrew/Cellar/node/21.0.0

CLI

Command-Line Interface — a text-based interface for interacting with your computer through typed commands in a terminal. macOS includes Terminal.app by default, but power users often switch to alternatives like Warp, iTerm2, or Ghostty for additional features.

DMG

Disk Image file — the traditional macOS installer format. A .dmg file mounts as a virtual disk and typically contains an app that you drag to the Applications folder. Homebrew Cask automates this process, eliminating the need to manually download and install DMG files.

Related:CaskHomebrew

Dotfiles

Configuration files whose names start with a period (dot), making them hidden by default in macOS. Examples include .zshrc (shell config), .gitconfig (Git settings), and .vimrc (Vim config). Developers version-control their dotfiles on GitHub to maintain consistent setups across machines.

Related:ShellCLI

Formula

A Homebrew package definition for command-line tools and libraries. Formulae are Ruby scripts that describe how to download, compile, and install software. Examples include git, node, python, and ffmpeg.

brew install git
Related:HomebrewCask

Gatekeeper

The macOS security feature that verifies downloaded apps are from identified developers and free of known malware. When you install an app via Homebrew Cask, Gatekeeper may prompt you to approve the first launch. Apps from the Mac App Store bypass Gatekeeper because Apple has already reviewed them.

Related:Sandbox

Homebrew

The most popular package manager for macOS. Homebrew installs command-line tools and desktop applications that Apple does not ship by default. It uses Ruby and Git under the hood and stores packages in /opt/homebrew on Apple Silicon Macs.

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

Keg

A specific installed version of a Homebrew formula. When you install git via Homebrew, the keg at /opt/homebrew/Cellar/git/2.43.0 contains the actual binaries and files. "Keg-only" formulas are installed but not symlinked into the system PATH to avoid conflicts.

Open Source

Software whose source code is publicly available for anyone to inspect, modify, and distribute. Many Mac apps on Bundl.run are open source, hosted on GitHub, and free to use. Open-source alternatives often replace expensive paid software — for example, OBS replaces paid screen recorders.

Package Manager

Software that automates installing, upgrading, and removing programs. On macOS, Homebrew is the de facto standard package manager. Package managers resolve dependencies, verify checksums, and keep software up-to-date. The command "brew update && brew upgrade" updates all installed packages.

brew update && brew upgrade
Related:Homebrew

Rosetta 2

Apple's translation layer that allows Intel (x86_64) Mac applications to run on Apple Silicon (ARM) Macs. It translates apps at installation or runtime with minimal performance overhead. Most popular apps now ship native Apple Silicon builds and no longer need Rosetta.

Sandbox

A macOS security feature that restricts what an application can access on your system. Sandboxed apps (common in the Mac App Store) have limited access to files, network, and system resources. Homebrew apps are typically NOT sandboxed, giving them full system access.

Related:Gatekeeper

Shell

The command interpreter that processes your terminal commands. macOS defaults to Zsh (Z Shell) since Catalina (2019). Other popular shells include Bash, Fish, and Nushell. Your shell configuration lives in files like .zshrc or .bashrc.

Related:CLITerminal

Tap

A third-party repository of Homebrew formulae and casks. Tapping adds a new source of packages beyond the default Homebrew Core and Homebrew Cask repositories. Organizations like Font Cask and individual developers maintain their own taps.

brew tap homebrew/cask-fonts

Terminal

An application that provides a command-line interface to the operating system. On macOS, Terminal.app is the built-in option, but third-party terminals like Warp (AI-powered), iTerm2 (customizable), Ghostty (GPU-accelerated), and Alacritty (minimal) offer enhanced features.

Related:CLIShell