Cosmic greetings, I am reading up on active galaxies, and 'strong' and 'broad' emission lines are mentioned everywhere, yet no definitions given. Do they mean that the object is emitting energy across a large part of the spectrum, or that it's emitting a lot of energy? Also, I am confused by the different types of active galaxies. I'm trying to work out the main ones though (I'm writing an essay and don't want to go into too much detail). Are they Seyfert, radio, blazars and quasars? Thank you for your time!