apt-get is a command-line tool which helps in handling packages in Linux. Its main task is to retrieve the information and packages from the authenticated sources for installation, upgrade and removal of packages along with their dependencies. Here APT stands for the Advanced Packaging Tool.

How sudo apt install works?

All packages required by the package(s) specified for installation will also be retrieved and installed. Those packages are stored on a repository in the network. So, apt-get downloads all the needed ones into a temporary directory ( /var/cache/apt/archives/ ). They will be downloaded from a web- or a ftp-server.

How does apt-get find packages?

apt-get searches for the specified package in the repositories given in the /etc/apt/sources. list file and /etc/apt/sources.