What does Ubuntu LTS mean?
LTS is an abbreviation for “Long Term Support”.
Ubuntu produce a new Ubuntu Desktop and Ubuntu Server release every six months. That means you'll always have the latest and greatest applications that the open source world has to offer. Ubuntu is designed with security in mind. You get free security updates for at least 9 months on the desktop and server.
A new LTS version is released every two years. In previous releases, a Long Term Support (LTS) version had three years support on Ubuntu (Desktop) and five years on Ubuntu Server. Starting with Ubuntu 12.04 LTS, both versions received five years support. There is no extra fee for the LTS version; we make our very best work available to everyone on the same free terms. Upgrades to new versions of Ubuntu are and always will be free of charge.
The LTS designation applies only to specific subsets of the Ubuntu archive. The LTS may not apply to all flavours and remixes of Ubuntu. For example, for 8.04 LTS, Kubuntu chose to move to KDE 4.0 and didn't issue an LTS release. In 10.04, the Netbook Edition was not an LTS. The project will decide which flavours will be LTS and the support duration for each, early in the LTS development cycle. Check Ubuntu Release Notes
