The answer is quite simple, digital patches are online greeting cards that you can send to other users which will show up on their profile page as a small picture icon. When you click on these little icons, it will display a larger sized image with a personal message explaining why the patch was awarded. There are a number of default images you can choose from, or you can upload your own.
For instance, if you really like a project someone has posted, you can send them a digital patch to let them know how awesome it is.
Or if someone subscribes to your feed, you can thank them by sending them a digital patch.
Or perhaps you just want to send lots of people virtual cookies for a good time. You can use digital patches to do that too!
Or if you want to start a club to honor everyone who has ever posted how to make a pocket protector, you can do that!
Or you can use it as a way to say hello to old friends by sending them a patch with their two favorite things.
Or perhaps you just want to brighten someone's day with some flowers.
Whatever is your impetus, by signing up for a pro account, you can receive a number of digital patches to distribute as you see necessary.