Every year, the first Saturday of May is Free Comic Book day at your local comic shops. The rules regarding who can actually get a free comic vary from shop to shop. Some only allow the comic to be free to kids under 13, while other shops give them away to anyone. And these are special comics that each publisher puts out for the day and are only available on Free Comic Day. As a lot of people want to collect them, some shops offer to sell a complete set without the shop’s stamp on them for about $1 an issue.
This year, Marvel has an issue of Spider-Man and a Captain America/Thor special and DC has a Green Lantern issue with a Flashpoint preview. For a full list of this year’s free comics; you can check out the official site right here.