Searching repository history
Logs are great, because we can search them. For all the details, see man git-log.
Here are some examples:
git log --author="John Doe"
git log --grep="bug #1234"
git log --grep bug
git log --since="2 weeks ago"
git log --until="yesterday"
# search for a commit with message and show the diff
git log --grep bug -p
# Search for a commit that changed a file
git log -- <file>
# Search for a commit that changed a file and show the diff
git log -p -- <file>