Yahoo! and Google have had a love/hate relationship for most of their respective history. Yahoo! was the undisputed leader among search engines for a long time, boasting the most search traffic. Their claim to fame was their human-edited database, comprised of sites that had been personally reviewed by an editor to make sure they fit the requirements, and were worthy of listing. Even if you paid a fee, listing was by no means guaranteed; I had more than one site rejected during Yahoo!'s glory days, forcing me to go back and re-work the site. The advantages to the searcher were obvious: Each site had, at some point, passed through a personal review to determine its value and relevance, so the results lacked the horrible spamming that plagued the automated search engines at that time.
On the other side of the fence was Google, the consummate automated search engine, an upstart start-up that began in someone's garage. From a small personal project, Google grew into a hugely popular search engine, featuring a database that anyone and everyone could get listed in, free of charge. On the downside, this meant that a lot of total garbage was getting listed. On the other hand, many small businesses could not or would not pay Yahoo!'s listing fee, so Google offered a more democratic and less commercial set of results.
Came the time when Yahoo! and Google forged an uneasy partnership. Yahoo! used Google for their "secondary search results", meaning that after all the Yahoo! sites were listed, they'd put up Google sites. Sometimes you'd see them (Yahoo! only had 43 sites that matched your search), sometimes you wouldn't (Yahoo! had 43,000 sites that matched your search!).
A couple of years ago, the internet underwent a sea change. Google climbed to the top of the heap, unseating longtime king Yahoo! from dominating the search engines. Yahoo!, bowing to the current reality, forged a new deal with Google. Now Google's results would be listed first and foremost, and Yahoo!'s own paid results would be the secondary listings, requiring a switch to a different set of search results entirely. If Yahoo! and Google both had a site listed, the Yahoo! description and category would be appended to the Google listing. Since Google also owned the primary listings on AOL and CNN, it was coming close to taking over the world.
In the last 4 months, that has all changed again. Yahoo! broke off their relationship with Google, purchased a number of other search engines (including Inktomi), and used their technology and databases to create their very own Yahoo! spider. This spider now provides primary search results for Yahoo!, Directory listings are still in a separate directory, and Google is out of the picture entirely. Google is poised to go public at long last, an IPO dangling on the horizon, and talks about new and innovative search strategies they are pursuing to keep their hold on the market. Yahoo! counters with similar talk. MSN threw their hat into the ring, and will be debuting their own spider later this year, along with new features.
The latest major shift resulted in more lost ground for Google. CNN will no longer use Google search results, and will use Yahoo!'s new spider results instead. How much of an impact this will have in the bigger scheme of things is uncertain, but neither search engine giant wants to lose any ground at this point. With their IPO looming, Google would obviously prefer not to show any loss of territory or dominance which could affect stock prices.
It seems inevitable that a final, epic battle of the search engines will be waged, and only one search engine can emerge the victor. Will Yahoo! regain their triumphant hold on #1? Will Google reclaim their recent dominance? Will MSN be the spoiler, who sneaks in the back door while the other two are busy destroying each other?
At least for now the end cannot be predicted. The only truly positive thing, from the search engine consumer's standpoint, is that the rivalries have spurred all the engines into making revolutionary and innovative changes to search engine technology and strategies, offering ever-more possibilities for the internet user, and vastly broadening the capabilities of search.