Google Drive is a popular cloud backup tool because it provides free storage. If you use Google Photos on your phone by default, it backs up your photos to Google Drive. Regular Google Photos users might also find their data plan mysteriously drying up unless they’re careful to set it to only use WiFi when it uploads. To set that correctly, open Google Photos and tap the hamburger button (the three stripes) at the top left. Now choose Settings, then Backup & sync, and look for Mobile Data Backup. Now uncheck the Photos button and Google Photos will now only back up your photos using WiFi.