Unless you have only one commit in your repository, no commit stands on it own and all commits can be related to each other. These relationships can be described in multiple ways, from exact revision walking paths to a vague 'are these commits even related'?| Git Cookbook
Want to know how old all your branches are? You can of course browse your logs, but git can tell you what you want to know in one command (if you're willing to call some shell golfing a single command)| Git Cookbook