How Do Search Engines Work – Web Crawlers 0
It is the search engines and the web crawler that finally bring your website to the notice of the prospective customers. Hence it is better to know how these search engines actually perform and how they present information to the customer initiating a search.
Two Types of SERPS
There are basically two types of search engines. The first is by robots called crawlers or web spiders. What these do is to crawl the web and check the quality of the results based on the info provided on the pages being crawled.
Spiders Index the Web
Search Engines use spiders to index and access websites. When you submit your website pages to a search engine by completing their required submission page, the search engine spider will index your entire site.
A ‘spider’ is an automated program that is run by the search engine system. Spider visits a web site, read the content on the actual site, the site’s Meta tags and also follow the links that the site connects.
Spiders Gather all the Information
The spider then returns all that information back to a central depository, where the data is indexed. It will visit each link you have on your website and index (include) those sites as well. Some spiders will only index a certain number of pages on your site, so don’t create a site with 500 pages!
The spider will periodically return to the sites to check for any information that has changed (looking for freshness of the written text). The frequency with which this happens is determined by the moderators of the search engine.
Spiders are Like a Book
A spider is almost like a book where it contains the table of contents, the actual content and the links and references for all the websites it finds during its search, and it may index up to a million pages a day, which is just a fraction of the web.
Example: Excite, Lycos, AltaVista and Google.
When you ask popular search engines to locate information, it is actually searching through the index which it has created and not actually searching the Web. Different search engines produce different rankings because not every search engine uses the same algorithm to search through the indices.
Keywords are Critical in Indexing a Site
One of the things that a search engine algorithm scans for is the frequency and location of keywords (keyword optimization - terms) on a web page, but it can also detect and you should avoid artificial keyword stuffing or spamdexing.
Then the algorithms analyze the way that pages link to other pages in the Web. By checking how pages link to each other, an engine can both determine what a page is about or focused on, if the keywords of the linked pages are similar to the keywords on the original page.
There is a basic overview of how a webcrawler search does its crawling around the web to find the popular search that the person typed in the SERPS and return the better results of all the sites it has in its index.
