SEO not only affects the search engine results, but also image search, video search and industry specific vertical search engines. It determines how a search algorithm functions and searches what is popular with people. When a website link is submitted to a search engine, a spider crawls through a page to gather links which lead to other pages and stores those pages on the server of the search engine. The information collected from these pages is sent to the indexer, whose job is to extract information from those pages such as the keywords and their weights, the location of the page and other links that are stored for the spider to crawl in future.
