A graphical WebBrowser released in the early 1990's. The first browser that showed inline images.
It was written by the NCSA, originally intended (I believe) to supersede their famous telnet(1) client.
The source code was eventually licensed to MicrosoftCorporation who wanted a browser in a hurry when they decided to compete in the browser market after all. A royalty was to be paid for every sold copy of the browser. Microsoft of course gave away the browser for free, and gave no royalties to Mosaic Spyglass.