Before you even start contemplating how to build your web site, you should know in what types of search engines it’s most important for your site to be ranked. Let’s face it: The search engine’s job is not easy. In my previous post, I have already mentioned about how search engines are divided into several types, beyond the primary, secondary, and targeted search. Take a look at your filing cabinet, multiply it by about a billion, and imagine someone throwing you a couple of words and then hovering impatiently behind you, tapping a toe, expecting you to find exactly the right document in the blink of an eye. In addition, search engine types are determined by how information is entered into the index or catalog that’s used to return search results. For search engines to bring back great results, they need to combine the best of both worlds: the speed of the machines and the intelligence of the human mind. These three types of search engines are
Crawler-based engines: To this point, the search engines discussed fall largely into this category. Crawler-based search engines, such as Google, create their listings automatically. The success of a crawler based search engine is directly related to the relevance (and speed) of the search results it returns. Crawler-based search engines have three major elements that are spider or crawler, index and search engine program. All the information collected by the crawler is returned to a central repository. This is called indexing. It is from this index that search engine results are pulled. Search engine software is the third part of a search engine. This is the program that sifts through the millions of pages recorded in the index to find matches to a search and rank them in order of what it believes is most relevant. Crawler-based search engines revisit web pages periodically in a time frame determined by the search engine administrator.
Hybrid search engines: a hybrid search engine is not entirely populated by a web crawler, or entirely by human submission. Hybrid search engines are both crawler based as well as human powered. In plain words, these search engines have two sets of listings based on both the mechanism mentioned above. the best example of hybrid search engine is Yahoo, which has got a human powered directory as well as search toolbar administered by Google. Although such engines provide both listings they are generally dominated by one of the two mechanisms. A hybrid is a combination of the two. In a hybrid engine, people can manually submit their web sites for inclusion in search results, but there is also a web crawler that monitors the Web for sites to include. Most search engines today fall into the hybrid category to at least some degree. Although many are mostly populated by crawlers, others have some method by which people can enter their web site information.
Human powered search engines: Search engines will make particular claims for their own methodology, all claiming that they provide better and more relevant rankings than the opposition. Human powered search engines are search engines which will have its results affected by human intervention, usually by people rating individual results further up or further down the rankings. Human-powered search engines rely on people to submit the information that is indexed and later returned as search results. Sometimes, human powered search engines are called directories. Yahoo! is a good example of what, at one time, was a human-powered search engine.
It’s important to understand these distinctions, because how your site ends up indexed by a search engine may have some bearing on when it’s indexed. For example, fully automated search engines that use web crawlers might index your site weeks (or even months) before a human-powered search engine. The reason is simple. The web crawler is an automated application. The human-powered search engine may actually require that all entries be reviewed for accuracy before a site is included in search results.