Tags

Figure 8 shows a press over one road. The road holds the commits in order. The brass plate is a tag. The press rivets the plate onto one commit.

What a tag is

A tag is a name for one commit. The name does not move. A tag stays on its commit for ever.

A tag and a branch are different

A branch name moves when you commit. The main branch points to the last commit of the road. The branch moves forward with each new commit.

A tag does not move. git tag v1.0 fixes the name v1.0 to one commit. A later commit does not change the tag.

Why this is important

A release has a tag. The name v1.0 must always mean the same code. A branch name cannot give this guarantee, because a branch moves.

Two types

A light tag is only a name for a commit. An annotated tag is a full object with its own message and date.

Use an annotated tag for a release.

Use the figure

1. Click the figure, or press the t key, to rivet the tag onto c3.
2. Look at the plate on the wagon.
3. A new commit, c4, then joins the road.

The pointer moves to c4. The plate stays on c3.