Edit: Due to the fact that this article is old, the installation instructions may not work anymore. In order to successfully install the latest version of Transmission, please access the transmission tag and open the latest article (the one on top).

The latest installation instructions for Transmission
Hello Linux Geeksters. As you may know, Transmission is an open-source bittorrent client, available on Linux systems. Due to the fact that it is built in either GTK and Qt, Transmission is installable on a lot of Linux systems. Among others, it can be used via the terminal or as a Web client, it has support for DHT, PEX, µTP and Magnet Link.
The latest version available is Transmission 2.83, which has been recently released. For information about this release, see the changelog.
In this article I will show you how to install Transmission 2.83 on Ubuntu 14.04 Trusty Tahr, Ubuntu 12.04 Precise Pangolin, Linux Mint 17 Qiana, Linux Mint 13 Maya, Pinguy OS 14.04, Pinguy OS 12.04, Elementary OS 0.3 Isis and Elementary OS 0.2 Luna.
Because it is available via PPA, installing Transmission 2.83 on the listed Ubuntu, Linux Mint, Pinguy OS and Elementary OS systems is easy. All you have to do is add the ppa to your system, update the local repository index and install the transmission package. Like this:
$ sudo add-apt-repository ppa:ricotz/unstable
$ sudo apt-get install update
$ sudo apt-get install transmission
The transmission package will install transmission-gtk for GTK based Desktop Environments (GNOME, Unity, XFCE, etc), and transmission-qt for Qt based DEs (KDE)
Optional, to remove transmission do:
$ sudo apt-get install transmission