Translations:Pacman Overview/37/en
From Manjaro
When pacman installs packages, it keeps a copy of all the old packages you have downloaded. This cache can be very useful if you have to install older packages in an emergency. However, left unchecked, this cache will grow very large over time. Systems running Pamac will already have access to its automated pacman cache cleaning functions. It is also possible to clean them manually using pacman.