LTS stands for "Long Term Support release". These Ubuntu releases are considered to be especially stable and receive official support longer than normal releases. A new LTS comes out every 2 years.
The LTS (Long Term Support) releases that have come out so far include:
- 6.06 Dapper Drake (no longer supported)
- 8.04 Hardy Heron (no longer supported on desktops; server edition supported until April 2013)
- 10.04 Lucid Lynx (desktop supported until April 2013, server supported until April 2015)
- 12.04 Precise Pangolin (desktop and server both supported until April 2017)
Unlike regular releases of Ubuntu, LTS releases can be upgraded directly from one to the next, without the need to upgrade to all intermediate releases in between.
For example, an Ubuntu 10.04 LTS system can be upgraded directly to Ubuntu 12.04 LTS. In contrast, an Ubuntu 10.10 system would have to be upgraded to 11.04, and then to 11.10, and then finally to Ubuntu 12.04 LTS.