There actually is a bit of logic involved, but there's definitely a lot of guessing. :)
What is the logic part though? I've never gotten that haha.
Well the number on the square after you click it tells you how many bombs (or whatever they are) are next to it. A lot of it is just guessing/luck, but once you've clicked enough squares, you can sorta use the numbers to figure out where the bombs are. (It's difficult though, and I've actually gotten further by clicking randomly)