Jpop and Jrock is short for "Japanese Pop' and "Japanese Rock". Basically it's pop and rock music from Japan.
Well, that might be debatable. Most of the time I hear anime fans talk about "J-Rock," they're talking about either very pop oriented bands or visual kei (glam/goth/hair metal/and so on). I don't think I've ever heard anyone other than myself refer to punk bands like Guitar Wolf or retro-rock bands like Thee 50's High Teens as J-Rock (heck, not even Shonen Knife!)
Then again, doesn't really say anything about the deffinition of J-Rock, just what the people who invented the term usually listen to (most of the people who listen to Guitar Wolf or Thee 50's High Teen or so forth aren't the sort to use that kind of slang, I guess)
but I see many people talking about it and I have no idea what it is. Anyone care to clarify this for me? Thanks