What do you think of indie rock or "alternative rock"?
I like it! It's a nice change from the classic rock I normally listen to! Can you recommend a good group?
I'm a big fan of Green Day. They are an alt rock group. 
I didn't realize they were considered alt rock! I listened to them a lot back in the 90s!  When do you think alt rock got started?
It started with grunge and punk revival bands in the US and UK. Even though those bands became mainstream they still maintained their underground and outsider attitudes.