Mosaic offered many new web features, including support for video clips, sound, forms, bookmarks, and history files. “The striking thing about it was that unlike all the earlier X-browsers, it was all contained in a single file,” Gillies and Cailliau explain: Installing it was as simple as pulling it across the network and running it. Later on Mosaic would rise to fame because of the
tag that allowed you to put images inline for the first time, rather than having them pop up in a different window like Tim’s original NeXT browser did. That made it easier for people to make Web pages look more like the familiar print media they were use to; not everyone’s idea of a brave new world, but it certainly got Mosaic noticed.
“What I think Marc did really well,” Tim Berners-Lee later wrote, “is make it very easy to install, and he supported it by fixing bugs via e-mail any time night or day. You’d send him a bug report and then two hours later he’d mail you a fix.”
Perhaps Mosaic’s biggest breakthrough, in retrospect, was that it was a cross-platform browser. “By the power vested in me by nobody in particular, X-Mosaic is hereby released,” Andreeson proudly declared on the www-talk group on January 23, 1993. Aleks Totic unveiled his Mac version a few months later. A PC version came from the hands of Chris Wilson and Jon Mittelhauser. The Mosaic browser was based on Viola and Midas, the Computer History museum’s exhibit notes. And it used the CERN code library. “But unlike others, it was reliable, could be installed by amateurs, and soon added colorful graphics within Web pages instead of as separate windows.”