Using the apt-get application is the quickest way to find and install debian packages. The installation part is done by an application named dpkg. Dpkg doesn’t have to be used by apt-get, you can use it manually as well.
From the man dpkg command:
dpkg - a medium-level package manager for Debian
Whatever that means.
In keeping with GNU/Linux system security, only the superuser can use the dpkg application. Dpkg is a typical GNU/Linux application that is controlled by command-line switches. Possibly the most common use of dpkg is to install a local .deb file.
To install a .deb file, become root and use the command:
dpkg -i filename.deb
Dpkg can also be used to:
Some of the package manipulation commands are actually carried out by an application called dpkg-deb. In those cases, dpkg just acts as a front end to dpkg-deb and passes the commands to it.
Dpkg-deb can also be used to manipulate .deb files. Some of the more useful commands of dpkg-deb are:
dpkg-deb –show filename.deb