Search Engine Optimization (SEO): Maximizes search result exposure by targeting and driving Web traffic and ultimately delivering increased sales. The majority of search engine page results come from unpaid or organic search. SEO optimizes websites to ensure top search engine placement, such as Google, as only 15 percent of searchers continue beyond page one.
SEO may generate an adequate return on investment. However, search engines are not paid for organic search traffic, their algorithms change, and there are no guarantees of continued referrals. Due to this lack of guarantees and certainty, a business that relies heavily on search engine traffic can suffer major losses if the search engines stop sending visitors. Search engines can change their algorithms, impacting a website's placement, possibly resulting in a serious loss of traffic. According to Google's CEO, Eric Schmidt, in 2010, Google made over 500 algorithm changes – almost 1.5 per day. It is considered wise business practice for website operators to liberate themselves from dependence on search engine traffic. In addition to accessibility in terms of web crawlers (addressed above), user web accessibility has become increasingly important for SEO.
To give you an idea of just how much money is being spent on paid search, take a look at Google. Google's AdWords program is the most used pay-per-click (PPC) advertising program available today. While the tech giant owns YouTube and Android, among hundreds of other profitable brands, AdWords accounts for roughly 70% of their revenue -- which speaks wonders for its effectiveness.
SEO (search engine optimization) for organic search: SEO is a free method of SEM that uses a variety of techniques to help search engines understand what your website and webpages are about so they can deliver them to web searchers. These techniques include things like using titles, keywords and descriptions in a website and webpage's meta tags, providing relevant content on the topic, using various heading tags (i.e. ), and linking to and from quality online resources.
The term was first used by Internet theorist John Kilroy in a 2004 article on paid search marketing. Because the distinction is important (and because the word "organic" has many metaphorical uses) the term is now in widespread use within the search engine optimization and web marketing industry. As of July 2009, "organic search" is now common currency outside the specialist web marketing industry, even used frequently by Google (throughout the Google Analytics site, for instance).
Remember when you used to rely solely on search engines for traffic? Remember when you worked on SEO and lived and died by your placement in Google? Were you #1? Assured success. Well, okay, maybe not assured. Success only came if the keywords were relevant to your site users, but it was the only real roadmap to generating site traffic and revenue.