Yahoo!
As one of the oldest surviving portals (and the most successful), Yahoo! joined the search market later than Google, but has been able to keep a sizable portion of the search volume, by the sheer popularity of its portal and brand name. Yahoo! is the second most popular search destination, and has a less demanding algorithm, so newer sites have a better chance of ranking in Yahoo! in the short term (6 months)1. Some businesses prefer rankings in Yahoo! as most of the Yahoo! users tend to be more consumer-minded as opposed to people who use Google, who are more geared towards research.
To learn more about Yahoo! use the links below:
http://info.yahoo.com/
http://directory.yahoo.com/