What is LTS (Long Term Support)?

Question

I looked it up in Wikipedia, and there is only one line there. Anyone have a more detailed description for it? Ubuntu releases their OS with this notation, but I was unable to find a detailed description over what it means/includes. I've already read the Ubuntu notation but need a more general description, not how Ubuntu has implemented it.

Answer 1

In the Linux World, LTS and similar terms mean that the distribution stays stable. That means: You will not get any major functional upgrades (at least none that break compatibility in any way), but you will get security enhancements. One example of this is Red Hat Enterprise Server or CentOS, which only had PHP 5.1 and were not upgraded to 5.2, yet all 5.2 security upgrades were backported.

Think of it like this: If you are writing a custom piece of Software (say, a very special Apache module) today and the company guarantees 5 year support, that means that you can be very sure that your custom software still runs in 5 years because all of the interfaces and structures will remain the same.

In the Windows World, this is not as strict but similar. Microsoft supported Windows NT 4 for 10 Years, up to middle or end of 2006. It was long obsolete by then, having been succeeded by both Windows 2000 and XP/2003, but because companies either did not want to migrate yet or had custom software that is not compatible, Microsoft provided support and (security) upgrades until then.

If you like bulleted lists, long term support means:

• Stable Interfaces and "System Core"
• Gets Security updates
• (Usually) no or not much new functionality is added
• Gives companies safety when making plans, as they know: If we launch this today, it is guaranteed to run until Date X.
• Not usable in all situations. If you want bleeding edge, LTS Systems are almost certainly not for you, but even technology that is not that bleeding edge may not be added (i.e. Windows NT never got real USB Support, RedHat/CentOS ran PHP 5.1 instead of 5.2, even months after 5.2.0 was released)...
• The exact definition about what Long Term Support covers varies from vendor to vendor, you want to check with them before making a decision

Answer 2

From the Ubuntu Wiki:

LTS is an abbreviation for “Long Term Support”.

We issue a new desktop and 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 18 months on the desktop and server.

With the Long Term Support (LTS) version you get three years support on the desktop, and five years on the server. 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.

Answer 3

I don't believe "LTS" has any general definition, so any answer will have to focus on what Ubuntu mean by "Long Term Support"

But, just to add xsl's answer, using the LTS versions on servers allows you to have some confidence you can deploy servers which are going to be regularly patched but will not need upgrades of the entire OS.

Also, non-LTS Ubuntu upgrades need to be carried out in sequence, i.e. to go from 7.10 to 8.10, you would first need to upgrade to 8.04

With the LTS releases, there is a clear upgrade path from one LTS release to the next, i.e. from 6.06 you can go straight to 8.04