The first parent options allows you to ignore commits that are not the first parent. This can be very useful to figure out the series of changes a given file went through on a branch.

Marc G Gauthier

The `--first-parent` option in `git log` restricts the log to only follow the first parent commit after a merge, effectively ignoring commits that came in via merged branches. This is useful when you want to replay the history of a branch as it appeared linearly, without re-processing commits introduced through feature branch merges. A concrete example illustrates how a naive `git log` can produce confusing duplicate change entries when merges are involved, and how `--first-parent` resolves this by showing only the merge commit rather than each individual commit from the merged branch.

Git Log's --first-parent Option