1994 was a big year in the history of Web search. The first hierarchical directory, Galaxy, was launched in January and, in April, Stanford students David Filo and Jerry Yang created Yet Another Hierarchical Officious Oracle, better known as Yahoo!.

During that same month, Brian Pinkerton at the University of Washington released WebCrawler. This, the first true Web search engine, indexed the entire contents of Web pages, where previous crawlers had indexed little more than page titles, headings, and URLs. Lycos was launched a few months later.

By the end of 1995, nearly a dozen major search engines were online. Names like MetaCrawler (the first metasearch engine), Magellan, Infoseek, and Excite (born out of the Architext project) were released into cyberspace throughout the year. AltaVista arrived on the scene in December with a stunningly large database and many advanced features, and Inktomi debuted the following year.

Over the next few years, new search engines would appear every few months, but many of these differed only slightly from their competitors. Yet the occasional handy innovation would find its way into practical use. Here are a few of the most successful ideas from that time:

Go To (now Overture) introduced the concept of pay-per-click (PPC) listings in 1997. Instead of ranking sites based on some arcane formula, Go To allowed open bidding for keywords, with the top position going to the highest bidder. All major search portals now rely on PPC listings for the bulk of their revenues.

Meta search engines, which combine results from several other search engines, proliferated for a time, driven by the rise of pay-per-click systems and the inconsistency of results among the major search engines. Today, new metasearch engines are rarely if ever seen, but those that remain possess a loyal following. The current crop of metasearch engines display mostly pay-per-click listings

The Mining Company (now About) launched in February 1997, using human experts to create a more exclusive directory. Many topic-specific (vertical) directories and resource sites have been created since, but About remains a leading resource.

Direct Hit introduced the concept of user feedback in 1998, allocating a higher ranking to sites whose listings were clicked by users. Direct Hits data influenced the search results on many portals for a long time, but, because of the systems susceptibility to manipulation, none of todays search portals openly use this form of feedback. DirectHit was later acquired by Ask Jeeves (now Ask), and user behavior may well be factored into the Ask/Teoma search results we see today.

Pay-to-play was introduced, as search engines and directories sought to capitalize on the value of their editorial listings. The LookSmart and Yahoo! directories began to charge fees for the review and inclusion of business Websites. Inktomi launched paid inclusion and trusted feed, allowing site owners to ensure their inclusion (subject to editorial standards) in the Inktomi search engine.

The examination of linking relationships between pages began in earnest, with AltaVista and other search engines adding link popularity to their ranking algorithms. At Stanford University, a research project created the Backrub search engine, which took a novel approach to ranking Web pages.