Use the apt package manager with apt, aptitude, apt-get and apt-cache— Cheat Sheet Linux
Repositories are remote locations from which packages can be downloaded and installed. Commands starting with
apt allow to manipulate these packages and their dependencies.
/etc/apt/sources.list file contains one or more remote repository locations.
/etc/apt/sources.list.d directory contains files defining remote repository locations (binaries and package sources) of packages. For example,