LTS stands for Long-term support, which is a product lifecycle management policy in which a stable release of computer software is maintained for a longer period of time than the standard edition. The LTS version of software is published in parallel with the STS (short-term support) edition. LTS applies the tenets of reliability engineering to the software development process and software release life cycle. Long-term support extends the period of software maintenance; it also alters the type and frequency of software updates (patches) to reduce the risk, expense, and disruption of software deployment, while promoting the dependability of the software.

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. In the case of Ubuntu, LTS releases are supported and maintained with security updates and bug fixes for five years after the initial release. LTS releases are recommended for production-ready consumers, businesses, and enterprises because you get years of software support and no system-breaking changes with software updates.