Because Debian Linux distro has it’s way of testing packages before they end up in the stable version, these packages might be sometimes outdated or you just wand to benefit from the newest functionalities for some packages. Debian Backports is a repository that you can use for these cases.
In order to use the repository we need to edit the file /etc/apt/sources.list and add this line:
deb http://http.debian.net/debian wheezy-backports main
Then either you could do the installations like:
apt-get -t squeeze-backports install "package"
either you could use this repository’s packages as default ones by creating a file named /etc/apt/preferences.d/backports with the following contents:
Package: * Pin: release a=wheezy-backports Pin-Priority: 600
Then all you need to do is
apt-get update && apt-get dist-upgrade
You can find a list of available packages here.