How to read git log graph

Question

In the git community book, it says

Another interesting thing you can do is visualize the commit graph with the \'--graph\' option, like so:

Answer 1

The asterisks show where something was committed:

e1193f8, 5a09431 and 30e367c were committed to the left branch (yielding a | on the right branch) whereas 420eac9 was committed to the right branch (yielding a | on the left branch). And that is what 420eac9 does different from the rest: it's the only commit to the right branch.

For the sake of completeness:

• d6016bc was the branching point
• 5e3ee11 is the merging commit
• 2d3acf9 is the first commit after merging

Answer 2

420eac9 is on a different branch than the 3 commits "below" it. The branches diverged after d6016bc and they were merged in 5e3ee11.