A tap is Homebrew-speak for a Git repository containing extra formulae. Homebrew has the capability to add (and remove) multiple taps to your local installation with the brew tap and brew untap commands. Type man brew in your terminal. The main repository at https://github.com/Homebrew/homebrew-core, often called homebrew/core, is always built-in.
Your taps are Git repositories located at $(brew --repository)/Library/Taps.
homebrew-ffmpeg/ffmpeg: A tap for FFmpeg with additional options, including nonfree additions.
denji/nginx: A tap for NGINX modules, intended for its nginx-full formula which includes more module options.
InstantClientTap/instantclient: A tap for Oracle Instant Client. The packages need to be downloaded manually.
osx-cross/avr: GNU AVR toolchain (Libc, compilers and other tools for Atmel MCUs, useful for Arduino hackers and AVR programmers).
petere/postgresql: Allows installing multiple PostgreSQL versions in parallel.
osrf/simulation: Tools for robotics simulation.
brewsci/bio: Bioinformatics formulae.
davidchall/hep: High energy physics formulae.
lifepillar/appleii: Formulae for vintage Apple emulation.
© 2009–present Homebrew contributors
Licensed under the BSD 2-Clause License.
https://docs.brew.sh/Interesting-Taps-and-Forks