Git tag

同大多数 VCS 一样，Git 也可以对某一时间点上的版本打上标签。人们在发布某个软件版本（比如 v1.0 等等）的时候，经常这么做。这样做的作用是：

Git tags are like milestones, markers or a specific point in the repo’s history marked as significant. Tags are usually used to mark stable releases or achievement of very important milestones.
Tags can help the users of the repo to easily navigate to the important parts of the code history like release points. For example, on Github, you can easily grab archive of “tags” in the current repo.
Ref: http://masnun.com/2012/06/28/tagging-in-git-why-how.html

附：

1. git tag具体操作方法参考
2. Some other info about Release: Release Your Software