Some search engines use software programs known as crawlers, robots or spiders.
These programs follow hyperlinks from one webpage to the next around the Web. When a crawler discovers a new site or page, it automatically adds it to the search engine index. Other search engines require you to submit information about your website to them directly before they will list it. See the How to Submit to Search Engines tutorial for more information and direct links to two search engine submission pages. Each search engine uses a complicated formula or algorithm that determines where you will appear on their list when someone performs a search.