There were little "pills" years ago called prime tabs then other similar and now fizz drops. All just compacted sugar. Makes bottling a little easier especially if you want to only do a few. For 5 gallons it's worth mixing up priming sugar with your brew in a bucket.
@sneezles61 I will also always think of it as the Flars method. I have been using it when bottling in 25oz PET bottles by using two. Just a bit undercarbed last time but they have been sitting for 6 months waiting for our return south so we shall see. I always had trouble figuring out how many prime tabs to use use too.
Miss Flars around here. When we moved to the new forum format I hated it and resisted. Flars instead read up on how it worked and helped me out a few times with it.