commits, one of them tagged, and with branch 'master' checked out:
------------
- HEAD (refers to branch 'master')
- |
- v
+ HEAD (refers to branch 'master')
+ |
+ v
a---b---c branch 'master' (refers to commit 'c')
^
|
------------
$ edit; git add; git commit
- HEAD (refers to branch 'master')
- |
- v
+ HEAD (refers to branch 'master')
+ |
+ v
a---b---c---d branch 'master' (refers to commit 'd')
^
|
------------
$ git checkout master
- HEAD (refers to branch 'master')
+ HEAD (refers to branch 'master')
e---f |
/ v
a---b---c---d branch 'master' (refers to commit 'd')