What's the difference between those coins? Does it have the same prices? Though I only hear about bitcoin a lot. What's altcoin, litcoin and dogecoin got to do?
They are copies of bitcoin that some greedy persons made
They really often introduce no important features and sometimes contain viruses but try to fool noobs into thinking they are much more robust/safe/fast/beautiful/practical/whatever than Bitcoin
You can trade them in several places (keep in mind that pump&dumps are the way to go there)