A .deb is a software package file containing application files of a particular software and metadata file about its dependencies and versions. The software
Ubuntu has four standard repositories where software packages are stored: Main, Universe, Restricted, and Multiverse. Main: Free and Open Source Software supported by Canonical.
‘Universe‘ is one of the standard repositories in Ubuntu, which contains community maintained free and open-source software, as opposed to ‘Main‘, which contains free
apt (Advanced Packaging Tool) is the package installation and dependency management tool in Debian and other Debian-based distributions. It works on top of ‘Dpkg‘