Debian, as a Linux distribution, has all of the inherent properties of the Linux kernel. Debian is well known for it's portability and reliability, running on many servers and supporting close to a dozen CPU architectures. One of the most distinguishing features of Debian, though, is it's package management system. Package management is the process of making sure that the kernel, programs, and libraries are up to date, and installed and configured properly. A simple command-line utility called apt can do all of these things.
apt-get update
This command checks the repository (a server where the programs are stored) for updates.
apt-get upgrade
This command upgrades any installed programs / libraries.
apt-get install packagename
This command installs a program or library.
apt-get remove packagename
This command uninstalls a program or library.