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# 1.2. What does a LAMMPS version mean

The LAMMPS “version” is the date when it was released, such as 1 May 2014. LAMMPS is updated continuously, and with the help of extensive automated testing (mostly applied before changes are included) we aim to keep it working correctly and reliably at all times, but there also are regular feature releases with new and expanded functionality, and there are designated stable releases that receive updates with bug fixes back-ported from the development branch.

In addition to automated testing, several variants of static code analysis are run regularly to maintain or improve the overall code quality, consistency, and compliance with programming standards, best practices and style conventions. You can follow its development in a public git repository on GitHub.

Each version of LAMMPS contains all the documented features up to and including its version date. For recently added features, we add markers to the documentation at which specific LAMMPS version a feature or keyword was added or significantly changed.

## 1.2.1. Identifying the Version

The version date is printed to the screen and log file every time you run LAMMPS. There also is an indication, if a LAMMPS binary was compiled from version with modifications after a release, either from the development version or the maintenance version of the last stable release. It is also visible in the file src/version.h and in the LAMMPS directory name created when you unpack a downloaded tarball. And it is on the first page of the manual.

- If you browse the HTML pages of the online version of the LAMMPS manual, they will by default describe the most current feature release version of LAMMPS. In the navigation bar on the bottom left, there is the option to view instead the documentation for the most recent stable version or the documentation corresponding to the state of the development branch develop.

- If you browse the HTML pages included in your downloaded tarball, they describe the version you have, which may be older than the online version.

## 1.2.2. LAMMPS releases, branches, and tags

Relations between releases, main branches, and tags in the LAMMPS git repository

### Development

Modifications of the LAMMPS source code (like bug fixes, code refactoring, updates to existing features, or addition of new features) are organized into pull requests. Pull requests will be merged into the develop branch of the LAMMPS git repository on GitHub after they pass automated testing and code review by core LAMMPS developers.

### Feature Releases

When a sufficient number of new features and updates have accumulated and the LAMMPS version on the develop branch passes an extended set of automated tests, we release it as a feature release, which are currently made every 4 to 8 weeks. The release branch of the git repository is updated with every such feature release and a tag in the format `patch_1May2014` is added. A summary of the most important changes of these releases for the current year are posted on this website page. More detailed release notes are available on GitHub.

### Stable Releases

About once a year, we release a stable release version of LAMMPS. This is done after a “stabilization period” where we apply only bug fixes and small, non-intrusive changes to the develop branch but no new features to the core code. At the same time, the code is subjected to more detailed and thorough manual testing than the default automated testing. After such a stable release, both the release and the stable branches are updated and two tags are applied, a `patch_1May2014` format and a `stable_1May2014` format tag.

### Stable Release Updates

Between stable releases, we collect bug fixes and updates that are back-ported from the develop branch in a branch called maintenance. From the maintenance branch we make occasional stable update releases and update the stable branch accordingly. The first update to the `stable_1May2014` release would be tagged as `stable_1May2014_update1`. These updates contain no new features.