Marvel comics originated from a company called pulp fantasy. During, the 1930s and 1940s, Pulp Fantasy released comics whose storyline involved patriotic idols (i.e. Captain America) who were supposed to  influence the youth of America by twisting storylines that defeated the German image, during the second world war. To see an example of a comic released by Marvel Comics, click here. These comics captivated the attention of America's youth and the soldiers who were currently at war. 

http://www.comic-art.com/history/history9.htm

The first marvel comic was released in October 1939. The comic's storyline revolved around the human torch (a.k.a. Johnny Storm, a member of the fantastic four) and Submariner. A character who still resides in today's comic books. 

After the comic boom of the 1940s, marvel was mass producing 80 comics per month.

Inspired by the success of DC’s Justice league, Marvel was influenced to create superheroes that would change the face of the company.  In the 1960s, Stan Lee was asked to come up with a new line of superheroes that would soon raise profits over the roof. 

The first range of superheroes was the fantastic four.  The fantastic four is a family of humans who acquired their super powers while passing through a storm of cosmic rays.  The original release of the Fantastic Four included: Mr. Fantastic, The Invisible Girl, Johnny (a.k.a. an updated version of the human torch) and the Thing.

A year after the release of the fantastic four, the incredible hulk hit the newsstands in Tales to Astonish.  By the next year, Hulk had his own comic book that was making record sales.

http://www.killermovies.com/images/movies/hulk.jpg

Spiderman, the most popular marvel superhero, was actually an idea that was about to be dropped.  He first appeared in Amazing Fantasy issue 15, which was released in March 1963.  It was later popularized with a TV show.

http://ksacomics.com/af15/15.JPG

During this period of comic book history, a ton of new interesting characters were introduced.  Although, they weren’t as popular as Spiderman or the Hulk, they created an atmosphere in which the Marvel industry would be revolutionized forever.  Stan Lee used these new characters as tools that would be used to overlap storylines.  For example, Ant man could star in a Spiderman Comic whose storyline continued in a Hulk Comic.

The introduction of these crossover storylines led to the creation of the X-men.  The X-men was a team of mutant teenagers who were apprentices of Professor Xavier.  The comic revolved around a team of superheroes instead of a specific character.  Nowadays, writers overuse this method. 

http://www.delos.fantascienza.com/delos60/img/singe

r/x-men-fumetto.jpg

Click here for another x-men group picture