A friend of mine claims that the holocaust is not entirely true, and it was not just the Jewish that were killed. I googled for a bit and the only things I find are conspiracy theories. Would someone care to clarify. Thank you for your time.
The Holocaust isn't an exaggeration, but your friend is not incorrect when saying that Jews were not the only victims. While Jews were the most significant target, Soviet POWs, Poles, Romani, the disables, gays, and various other groups were targeted.
There is a good deal of information about holocaust denial in the popular questions.