The leading search engines, such as Google, Bing and Yahoo!, use crawlers to find pages for their algorithmic search results. Pages that are linked from other search engine indexed pages do not need to be submitted because they are found automatically. The Yahoo! Directory and DMOZ, two major directories which closed in 2014 and 2017 respectively, both required manual submission and human editorial review.[40] Google offers Google Search Console, for which an XML Sitemap feed can be created and submitted for free to ensure that all pages are found, especially pages that are not discoverable by automatically following links[41] in addition to their URL submission console.[42] Yahoo! formerly operated a paid submission service that guaranteed crawling for a cost per click;[43] however, this practice was discontinued in 2009.
Social media often feeds into the discovery of new content such as news stories, and “discovery” is a search activity. Social media can also help build links that in turn support into SEO efforts. Many people also perform searches at social media sites to find social media content. Social connections may also impact the relevancy of some search results, either within a social media network or at a ‘mainstream’ search engine.
Social media marketing provides organizations with a way to connect with their customers. However, organizations must protect their information as well as closely watch comments and concerns on the social media they use. A flash poll done on 1225 IT executives from 33 countries revealed that social media mishaps caused organizations a combined $4.3 million in damages in 2010.[93] The top three social media incidents an organization faced during the previous year included employees sharing too much information in public forums, loss or exposure of confidential information, and increased exposure to litigation.[93] Due to the viral nature of the Internet, a mistake by a single employee has in some cases shown to result in devastating consequences for organizations. An example of a social media mishap includes designer Kenneth Cole's Twitter mishap in 2011. When Kenneth Cole tweeted, "Millions are in uproar in #Cairo. Rumor has they heard our new spring collection is now available online at [Kenneth Cole's website]".[94] This reference to the 2011 Egyptian revolution drew an objection from the public; it was widely objected to on the Internet.[94] Kenneth Cole realized his mistake shortly after and responded with a statement apologizing for the tweet.[95] Avatars United Bebo Bolt Capazoo eConozco Emojli Eyegroove FitFinder Formspring FriendFeed Friends Reunited Friendster Google+ Google Buzz Heello Hyves iTunes Ping iWiW Jaiku LunarStorm Me2day Meerkat Mobli Mugshot Natter Social Network Netlog Orkut Pheed Piczo PlanetAll Posterous Pownce Qaiku Surfbook tbh Tsū tvtag Vine Windows Live Spaces Wretch Yahoo! 360° Yahoo! Kickstart Yahoo! Mash Yahoo! Meme Yik Yak
Optimization techniques are highly tuned to the dominant search engines in the target market. The search engines' market shares vary from market to market, as does competition. In 2003, Danny Sullivan stated that Google represented about 75% of all searches.[64] In markets outside the United States, Google's share is often larger, and Google remains the dominant search engine worldwide as of 2007.[65] As of 2006, Google had an 85–90% market share in Germany.[66] While there were hundreds of SEO firms in the US at that time, there were only about five in Germany.[66] As of June 2008, the market share of Google in the UK was close to 90% according to Hitwise.[67] That market share is achieved in a number of countries.