Search originates on the web – made up of more than 60 trillion pages of information and growing every day. Search engines, like Google, navigate the web and find your sites by called crawling, following links from page to page. These pages are sorted by their content and relevance to a topic and indexed to keep track of them and rank by relevance.
How do search engines find your site? Search engines create algorithms, or formulas, that deliver the best possible results. As people search for information, the engines look for clues to better understand what you mean, or the intent of your query? Based on these clues, the search engines pull relevant pages from the index and then rank the results. These results are based on over 200 factors, including freshness of content, page and site quality, and user context.
Search algorithms are constantly evolving, inspired by new ideas, experiments, and analytics by search engineers. The results manifest in a variety of forms on a web page, including rich snippets, knowledge graphs, images, videos, news and mobile designs. To keep the results relevant, search engines examine the content of a page and take action to remove spam.
Behind every page result is a complex system that supports over 100 billion searches every month. During the two minutes it took you to read this blog, about 5 million searches were performed.
Now that you know how search works, there are simple strategies that influence how your website will rank and be positioned:
You can read more from the source here: http://www.google.com/insidesearch/howsearchworks/thestory/
Source: Paid Search