Introduction to "Comic Book Numbering"
Comic book numbering used to be a very simple issue - each issue was incremented one number from the preceding issue in a simple natural number sequence starting at issue #1 until infinity.
Occasionally there would be some complications when a series was re-named (often when a key character in an ongoing anthology becomes popular enough for their own title), such as "The Incredible Hulk (1968)" taking over the numbering from "Tales to Astonish (1959)" or "Captain America (1968)" taking over the numbering of "Tales of Suspense (1959)".
However, DC Comics started an inadvertent trend when John Byrne re-structured the Man of Steel in the mid-1980's. All Superman comics (Action Comics and Superman) were taken offline for a few months, and a re-launch re-started Superman (1987) with a new #1, and continued the pre-existing Superman (1939) numbering with "Adventures of Superman (1987)". Superman (2006) re-merged Superman (1987) and Adventures of Superman (1987) to a single title.
Both DC and Marvel comics insisted on the occassional oddly numbered comic (0, -1 for Marvel, 1,000,000 for DC) which made continuity of numbering strange.
Marvel had a mathematical psychotic break and sold off key characters (e.g. Hulk, Avengers, Iron Man, Captain America and the Fantastic Four) to a group of artist/writers in the ill-fated "Heroes Reborn" period of about a year in the mid-1990's, each series being re-started as a new #1. This experiment lasted about a year from 1996 to 1997, where the characters were re-introduced into the "real" (616) universe of Marvel in "Heroes Return".
Marvel's marketing department, realizing that "#1" issues had extra purchase value, began randomly re-starting series to generate new #1's. Later, someone woke up and realized that they were missing the chance to capitalize on significant milestone issues (500, 600 etc.) and began to re-number the ongoing series, with mixed success. Some re-numbering was simply the inclusion of series X and series Y of the same character, with the new numbering being the sum. However, with other series, the effect was somewhat confusing (see Hulk).
This site is an attempt to make sense of the numbering issues.