Glitches are different to cheats. A cheating player will find and use cheats to get ahead in the game. A glitch is something which exists in the game by mistake. You can find the wiki entry on Roblox glitches here. Most glitches are daft little things and mostly cosmetic.
One of the more popular glitches is known as the 'flying brick' and is about as close as you get to a public Roblox flying cheat. If you added a welded and unanchored brick to your legs you would be able to walk and fly.
That said there was a glitch a while ago which allowed players to get lifetime OBC by changing the URL while they ordered. This kind of thing is obviously a little more than cosmetic and abusing these kind of glitches is grounds for being banned from the game. Glitches will always come and go as more are patched out and others are found and created. Here's a few examples of glitches, keeping in mind the video is pretty old and features mostly patched glitches but it should give you an idea.
It's pretty interesting that the 'hat explosion' glitch is now considered a feature. But then again Roblox wouldn't be the only game which adopted a glitch and made it part of the game. We try to keep track of the latest working glitches but you can also check our our full list of Roblox cheats which are a little different.