A command line utility to manage AUR (Arch Linux User Repository) packages. The AUR contains about any imaginable packages on Earth, it’s one of the greatest features of Arch. If you need some app, someone probably already packaged it in the AUR, so you don’t have to handle a manual update.
AUR helpers allow installing and updating both official Arch packages and AUR packages with a single command.
Another popular one that I use is yay.