Particularly, these four that people love to throw around
Emo
Screamo
Alternative
Indie
The first two essentially seem like the same as hardcore punk, the third seems to be essentially a buzzword for post grunge, and I have no idea what characteristics of a band's music makes them indie. So what characteristics of bands/artists causes them to be labeled as those four genres, in you opinion?
Also, what genres have you heard people using that you think are silly?