I'm very confused by how many different Spider-Man titles there have been. I understand that Amazing Spider-Man is the main one and that it's been going on pretty much continuously for like 40 years but where do Spider-Man, Peter Parker The Spectacular Spider-Man, Web of Spider-Man, etc. fit into this? I also understand the original book titled just Spider-Man was created for Todd McFarlane. Were any of the other Spider-Man titles created for a specific reason, either in continuity or in the real world? Or did they have no purpose beyond being just a second/third Spider-Man title?