What is SEO

SEO ( Search Engine Optimization ) - SEO stands for “search engine optimization.” It is the process of getting traffic from the free, organic and natural listings on search engines. All major search engines such asGoogle, Yahoo and Bing have such results, where web pages and other content such as videos or local listings are shown and ranked based on what the search engine considers most relevant to users. 
Search engines use specific algorithms to determine what website will be ranked higher for some particular query in search results. These algorithms are kept strictly confidential, but their general concepts and principles can be found if you spend some time and analyze search engine behavior.


Source: http://searchengineland.com/guide/what-is-seo