Hanukkah. And why is it spelled a million different ways?

I was raised Catholic and wasn't exposed to other religions until I got to college and spent time with people from religions other than my own. So, I'm curious how you spell Hanukkah (I spell it that way because that's what auto-correct tells me to do). And why are there so many different ways to spell it?

I know I could Google this but I'm just looking to hear from Bees.