Search engine optimization:  (SEO) is the procedure of improving the level or quality of traffic to a web site or a web page (such as a blog) from search engines via "natural" or un paid ("organic" or "algorithmic") search results as different to other forms of search engine marketing (SEM) which may deal with paid insertion. The theory is that the earlier or higher a site appear in the search results list, the more visitors it will be given from the search engines. SEO target may different kinds of search, with images search, local search, video search and industry specific vertical search engines. This gives a web site web attendance.

As an Internet marketing strategy, SEO considers how search engines work and what people search for. Optimizing a website chiefly involves editing its content and HTML and linked coding to both increase its significance to specific keywords and to remove barriers to the indexing activities of search engines.
The short form "SEO" can refer to "search engine optimizers" a term adopted by an industry of consultant who carry out optimization projects on behalf of customers, and by staff who perform SEO services in house. Search engine optimizers may offer SEO as a stand alone service or as a part of a broader marketing campaign.  Because effective SEO may require changes to the HTML source code of a site, SEO plans may be included into web site development and design. The term "search engine friendly" may be used to explain web site designs, menus, content management systems (CMS), images, videos, shopping carts, and other elements that have been optimized for the reason of search engine exposure.

Another class of technique, known as Black Hat SEO or spamdexing, uses method such as link farms, keyword stuffing and article rotating that degrade both the relevance of search results and the users experience of search engines. Search engines look for sites that use these technique in order to remove them from their index.