Have you ever given a thought on how Web Listings Inc. get the help of search engines to work on the internet?
When you use the term ‘search engine’ in relation to the Web, it is usually referring to the actual search forms that searches through databases of HTML documents, initially gathered by a robot. There are basically three types of search engines:
1. Search engines powered by robots (called crawlers; ants or spiders)
2. powered by human submissions and
3. A hybrid of these two
Now, let us go into more detail…
a) The “Crawler-based search engines” are those that use automated software agents (called crawlers) that visit a Web site, read the information on the actual site, read the site’s meta tags and also follow the links that the site connects to performing indexing on all linked Web sites as well. The crawler returns all that information back to a central depository, where the data is indexed. The crawler will periodically return to the sites to check for any information that has changed. The frequency with which this happens is determined by the administrators of the search engine.
b) Human-powered search engines basically rely on humans to submit information that is subsequently indexed and cataloged. Only information that is submitted is put into the index.
c) In both the above cases, when you query a search engine to locate the information, you’re actually searching through the index that the search engine has created – you are not actually searching the Web. These indices are giant databases of information that is collected and stored and subsequently searched. This explains why sometimes a search on a commercial search engine, such as Google or Yahoo! will return results that are in fact ‘dead links’. Since the search results are based on the index, if the index hasn’t been updated since a Web page became invalid the search engine treats the page as still an active link even though it no longer is. It will remain that way until the index is updated.
Now the updating part is always done by web SEO companies like Web Listings Inc. with the expert knowledge and techniques available.
