How to use the APT command on Ubuntu/Debian Linux systems ?

APT is one of the most frequently used commands in Ubuntu ( and Debian family hereafter ) . APT stands for Advanced Package Tool and is used as a package management (i.e. updating, adding or removing) utility. APT allows you to upgrade an entire set of softwares, applications and packages with a single command ( oftentimes, this will require root level permissions to execute it ).