How Search Engines Work

Before we have a tendency to begin talking regarding search engine optimization (SEO) we want to know how search engines work. Basically, every search engine consists of three parts:

1. The Crawler (or the spider). This a part of a quest engine may be a easy robot that downloads pages of an internet site and crawls them for links. Then, it opens and downloads every of these links to crawl (spider) them too. The crawler visits websites periodically to search out the changes in their content and modify their rankings accordingly. looking on the standard of an internet site and also the frequency of its content updates this might happen from say once per month up to many times daily for a high popularity news sites.
   
   The crawler doesn't rank websites itself. Instead, it merely passes all crawled websites to a different search engine module known as the indexer.
   
2. The Indexer. This module stores all the pages crawled by the spider during a giant database known as the index. consider it because the index during a paper book: you discover a word and see that pages mention this word. The index isn't static, it updates anytime the crawler finds a replacement page or re-crawls the one already presented within the index. Since the quantity of the index is extremely giant it usually takes time to commit all the changes into the database. therefore one might say that an internet site has been crawled, however not however indexed.
   
   Once the web site with all its content is added to the index, the third a part of the search engine begins to figure.
   
3. The ranker (or search engine software). This half interacts with user and asks for a quest question. Then it sifts scores of indexed pages and finds all of them that are relevant to that question. The results get sorted by relevance and at last are shown to a user.