If you haven't read it yet, here is the very funny history of browser user-agent string as narrated by Aaron Andersen of WebAIM. "In the beginning there was NCSA Mosaic, and Mosaic called itself NCSA_Mosaic/2.0 (Windows 3.1), and Mosaic displayed pictures along with text, and there was much rejoicing. And behold, then came a new web browser known as "Mozilla", being short for "Mosaic Killer", but Mosaic was not amused, so the public name was changed to Netscape, and Netscape called itself Mozilla/1.0 (Win3.1), and there was more rejoicing.
And Netscape supported frames, and frames became popular among the people, but Mosaic did not support frames, and so came "user agent sniffing" and to "Mozilla" webmasters sent frames, but to other browsers they sent not frames."
Through its time travel, Aaron lists with a lot a humor the evolving of the user-agent string: from Mosaic to Chrome, we can't help but smile at the vision of the web browser developers imagination.
"Then cometh Opera and said, "surely we should allow our users to decide which browser we should impersonate", and so Opera created a menu item, and Opera called itself Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; en) Opera 9.51, or Mozilla/5.0 (Windows NT 6.0; U; en; rv:1.8.1) Gecko/20061208 Firefox/2.0.0 Opera 9.51, or Opera/9.51 (Windows NT 5.1; U; en) depending on which option the user selected."
Refreshing, and funny!