Do you ever find yourself scrolling madly through your phone’s camera roll, looking for that one fabulous vacation shot you’re describing to a friend — and you can’t find it in the river of 4,000 photos? Or do you want to collect all the pictures of a child, scattered through the years, for a slide show but don’t have time to find them?

Herding pictures into sensible albums on the phone can be tedious if you bother at all, but here’s the good news: If you’ve been using the current versions of Google Photos on your Android or Apple device or Apple’s Photos for iOS, there’s a good chance that the apps have been organizing your images for you.

It can be a little unnerving to see how these apps have analyzed your pictures. But the software can save you hours and is simple to use. Here are ways to use the programs — and how to tweak them to adjust to your needs.