How Do Search Engines Work - Web Crawlers
It is the search engines that finally bring your website to the notice of the prospective customers. Hence it's better to know how these search engines actually work and how they present information to the customer initiating a search.
There are basically two sorts of search engines. the primary is by robots called crawlers or spiders.
Search Engines use spiders to index websites. once you submit your website pages to a search engine by completing their required submission page, the program spider will index your entire site. A ‘spider’ is an automatic program that is run by the search engine system. Spider visits an internet site, read the content on the particular site, the location 's Meta tags and also follow the links that the site connects. The spider then returns all that information back to a central depository, where the info is indexed. it'll visit each link you have on your website and index those sites as well. Some spiders will only index a specific number of pages on your site, so don’t create a site with 500 pages!
The spider will periodically return to the sites to test for any information that has changed. The frequency with which this happens is decided by the moderators of the search engine.
A spider is nearly like a book where it contains the table of contents, the particular content and the links and references for all the websites it finds during its search, and it's going to index up to a million pages a day.
Example: Excite, Lycos, AltaVista and Google.
When you ask a search engine to locate information, it's actually searching through the index which it has created and not actually searching the Web. Different program s produce different rankings because not every search engine uses the same algorithm to search through the indices.
One of the things that a search engine algorithm scans for is the frequency and location of keywords on a web page, but it also can detect artificial keyword stuffing or spamdexing. Then the algorithms analyze the way that pages link to other pages within the Web. By checking how pages link to every other, an engine can both determine what a page is about, if the keywords of the linked pages are almost like the keywords on the original page.