apt-get's commands are very easy and intuitive.
Its commands follow this structure:
# apt-get [options] command # apt-get [options] install package [package ...]
The command line may be a variation of the following basic types:
Updates apt-get's local database with server's pkglist's files.
verifies system's integrity using apt
installs some new package, automatically resolving and downloading dependent packages
checks for outdated packages in the system and automatically upgrades them
same as apt-get upgrade, but installs all base packages and tries to upgrade everything, installing new packages if needed
removes the some-package package and all other packages that depends on it
removes the downloaded packages from the cache directory (/var/cache/apt/archives/), freeing some disk space at your system ;-)