citric acid ... what do I do with this stuff?

I was in my local cake supply store today and noticed a bottle of citric acid. I bought some because I vaguely remembered some craft soap/bath fizzies recipes that I wanted to try called for it. But of course, I didn’t know for bath stuff you need the powdered kind, and I of course bought the liquid kind.

So … what do sugar artists do with this stuff? CK Products’ website says “Citric Acid adds tartness to candy and recipes.” Does it do anything else?

I’m willing to try new things. The bottle was inexpensive, so I won’t even bother returning it if I can try something out.