Altbier? Lager? Festbier?…

So I’m new to beer. And honestly drinking in general. So I’ve been trying to figure out what I like. I’ve been seeing some terms lately I’m unfamiliar with and want to know what they mean. I’m having an Old Man Copper at the moment. It’s an altbier apparently. Unsure of what that means. I had a different beer in Georgia a while back that I really liked that was a festbier. And of course I’ve heard lager on about half the beer commercials I’ve seen. So what are they? What makes them different? Thanks for your time