git tag is used to create labels, usually for version numbers.
Format： git tag <TagName> <refer>
Example：
git tag v0.1 HEAD
is to create a version number v0.1 on current HEAD.
Notice:
When you git push your code to remote server, you need to add --tags option.
git push --tags
Delete local tags
git tag -d v1.0
Delete remote tags
git push origin :/refs/tags/v1.0