GitHub link for those who don't know about it: https://github.com/ggreer/the_silver_searcher/

I built ag for searching code. It can be (ab)used for other stuff, but the defaults are optimized for a developer searching a codebase. Also, when writing ag, I don't go out of my way to make sure behavior is correct on all platforms in all corner cases. Grep, on the other hand, has been around for decades. It probably handles cases I've never even thought of.