Social media marketing involves the use of social networks, consumer's online brand-related activities (COBRA) and electronic word of mouth (eWOM)[75][76] to successfully advertise online. Social networks such as Facebook and Twitter provide advertisers with information about the likes and dislikes of their consumers.[61] This technique is crucial, as it provides the businesses with a "target audience".[61] With social networks, information relevant to the user's likes is available to businesses; who then advertise accordingly. Activities such as uploading a picture of your "new Converse sneakers to Facebook[75]" is an example of a COBRA.[75][76] Electronic recommendations and appraisals are a convenient manner to have a product promoted via "consumer-to-consumer interactions.[75] An example of eWOM would be an online hotel review;[77] the hotel company can have two possible outcomes based on their service. A good service would result in a positive review which gets the hotel free advertising via social media. However, a poor service will result in a negative consumer review which can potentially harm the company's reputation[78].

Companies that employ overly aggressive techniques can get their client websites banned from the search results. In 2005, the Wall Street Journal reported on a company, Traffic Power, which allegedly used high-risk techniques and failed to disclose those risks to its clients.[15] Wired magazine reported that the same company sued blogger and SEO Aaron Wall for writing about the ban.[16] Google's Matt Cutts later confirmed that Google did in fact ban Traffic Power and some of its clients.[17]
Search engines use complex mathematical algorithms to interpret which websites a user seeks. In this diagram, if each bubble represents a website, programs sometimes called spiders examine which sites link to which other sites, with arrows representing these links. Websites getting more inbound links, or stronger links, are presumed to be more important and what the user is searching for. In this example, since website B is the recipient of numerous inbound links, it ranks more highly in a web search. And the links "carry through", such that website C, even though it only has one inbound link, has an inbound link from a highly popular site (B) while site E does not. Note: Percentages are rounded.
Optimizing a website may involve editing its content, adding content, modifying HTML, and associated coding to both increase its relevance to specific keywords and to remove barriers to the indexing activities of search engines.[citation needed] 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.[3]