The first real tabbed browser with any significant presence on the web was
Netcaptor, created by the very talented
Adam Stiles way back in 1997.
The next major implementation of tabbed browsing was the work of HJ van Rantwijk with MultiZilla, a tabbed browsing extension for Mozilla that copied pretty much everything that Adam had done in Netcaptor. HJ launched this extension for Mozilla back in 2000.
In
September of 2001, Dave Hyatt added a tabbed browsing mode to Mozilla.
This feature was release in Mozilla 0.9.5 in
October of 2001
In
December of 2001, Opera Software released version 6 of its Opera browser which was the first version to contain a genuined tabbed browsing mode (along with its SDI and MDI modes).
In
September of 2002, Phoenix 0.1 (which would eventually be renamed to Firefox) shipped its first release which contained the most usable tabbed browsing implemenatation to date ;-)
In
January of 2003, Apple introduced the Safari web browser which contained a very nice tabs implemenation.
In
May of 2005, Microsoft announced that IE 7 (due later in the year) would have a tabbed browsing interface. The MSN team at Microsoft shipped a tabs-capable toolbar for IE 6 in June of 2005.