Search engine optimization (SEO) is the process of increasing the quality and quantity of website traffic by increasing the visibility of a website or a web page to users of a web search engine.

SEO refers to the improvement of unpaid results (known as “natural” or “organic” results) and excludes direct traffic/visitors and the purchase of paid placement.

SEO may target different kinds of searches, including image search, video search, academic search, news search, and industry-specific vertical search engines.

Optimizing a website may involve editing its content, adding content, and modifying HTML and associated coding to both increase its relevance to specific keywords and remove barriers to the indexing activities of search engines. Promoting a site to increase the number of backlinks, or inbound links, is another SEO tactic. By May 2015, mobile search had surpassed desktop search.

As an Internet marketing strategy, SEO considers how search engines work, the computer-programmed algorithms that dictate search engine behavior, what people search for, the actual search terms or keywords typed into search engines, and which search engines are preferred by their targeted audience. SEO is performed because a website will receive more visitors from a search engine the higher the website ranks in the Search Engine Results Page (SERP). These visitors can then be converted into customers.

SEO differs from local search engine optimization in that the latter is focused on optimizing a business’ online presence so that its web pages will be displayed by search engines when a user enters a local search for its products or services. The former instead is more focused on national or international searches.As marketing strategy
SEO is not an appropriate strategy for every website, and other Internet marketing strategies can be more effective, such as paid advertising through pay per click (PPC) campaigns, depending on the site operator’s goals.

Search engine marketing (SEM) is the practice of designing, running and optimizing search engine ad campaigns. Its difference from SEO is most simply depicted as the difference between paid and unpaid priority ranking in search results. Its purpose regards prominence more so than relevance; website developers should regard SEM with the utmost importance with consideration to visibility as most navigate to the primary listings of their search.

A successful Internet marketing campaign may also depend upon building high quality web pages to engage and persuade, setting up analytics programs to enable site owners to measure results, and improving a site’s conversion rate. In November 2015, Google released a full 160 page version of its Search Quality Rating Guidelines to the public, which revealed a shift in their focus towards “usefulness” and mobile search. In recent years the mobile market has exploded, overtaking the use of desktops, as shown in by StatCounter in October 2016 where they analyzed 2.5 million websites and found that 51.3% of the pages were loaded by a mobile device. Google has been one of the companies that are utilizing the popularity of mobile usage by encouraging websites to use their Google Search Console, the Mobile-Friendly Test, which allows companies to measure up their website to the search engine results and how user-friendly it is.