During his course of studies he worked at the National Center for Supercomputing Applications of the university and dealt with the open standards for WWW by Tim Berners-Lee.
Along with Eric Bina he developed a user friendly graphical browser called Mosaic.
According to Bina they worked for three or four days straight until they were completely exhausted and rested for an entire day.
In California Andreessen met Jim Clark, the founder of Silicon Graphics, who was aware of the commercial possibilities of Mosaic immediately.
They founded the Mosaic Communications Corporation together, Andreessen became vice president.
Since the University of Illinois had a problem with the company name containing the word “Mosaic”, the name was changed to Netscape Communications and their flagship was the Netscape Navigator.
Due to the success of Netscape, Andreessen became the child prodigy of the internet boom and was on the front cover of People Magazine and some other magazines.
Microsoft recognized the potential of the WWW, copyrighted the Mosaic source code from Spyclass Inc. (part of the University of Illinois) and “developed” Internet Explorer.
The resulting competition between Netscape and Microsoft is known as “browser wars”.
In 1999 Netscape was taken over by AOL for 4.2 billion dollar.