Google Photos Backup is a simple tool which automatically backs up pictures from your PC, camera or memory card, to your Google Photos cloud storage space.
(Google Photos is a free online space to store, organise and share your favourite photos. If you have a Google account then you can use Google Photos already. Check this page to see how much storage space you've got.)
The program is very easy to set up, and works much like any other continuous backup tool. Point Google Photos at the folders or devices containing your images, it backs up their contents, then watches for new images and backs them up as they arrive.
The Settings dialog provides a few more options. In particular, you can tell the program to also import photos and videos from external media to a local folder, convenient if you'd like to process them offline.
If you're short on bandwidth then your photo backups can be paused in a click or two.
A system tray icon also provides an option to "View Uploaded Photos", which opens a browser window at your Google Photos page.
Google Photos Backup is lightweight, easy to use, and works exactly as advertised. If you're not currently backing up your photos in some other way then it looks like a good choice.