Tag

Simply a way to mark specific commits as special in some way (ex. tag a specific commit as a specific release, or something along those lines)

• tags and branches are similar, in that they both point to a specific commit (ie. they are pointers to snapshots). Theoretically, branches could perform the role of tags. We could just keep around a branch called Release 2.0. Instead, Git allows us to separate concerns.
  • A branch is a moveable pointer to a snapshot, while tags point at a single snapshot and never move. Also, tags are actually stored as objects, while branches are not.
• if we are doing something a little risqué (like undoing a rebase), it's good to make a backup git tag BACKUP. Then if we ever need to go back to it, run git reset --hard BACKUP

Annotated vs. Lightweight Tags

There are 2 types of tag, lightweight and annotated

• lightweight - a reference to a commit that never moves
  • this type of tag does not create a tag object
• annotated - when we create an annotated tag, Git creates a tag object and then writes a reference point to it (rather than directly to the commit).
  • we usually want this one.

Inner

• The fourth (and less integral) object functions similar to a commit object, in that it contains a tagger, a message, a date, and a pointer.
  • The main difference is that a tag normally points to a commit rather than a tree. In this sense it is similar to a branch reference, but it never moves (ie. it always points to the same commit).