Websites such as Delicious, Digg, Slashdot, Diigo, Stumbleupon, and Reddit are popular social bookmarking sites used in social media promotion. Each of these sites is dedicated to the collection, curation, and organization of links to other websites that users deem to be of good quality. This process is "crowdsourced", allowing amateur social media network members to sort and prioritize links by relevance and general category. Due to the large user bases of these websites, any link from one of them to another, the smaller website may in a flash crowd, a sudden surge of interest in the target website. In addition to user-generated promotion, these sites also offer advertisements within individual user communities and categories. Because ads can be placed in designated communities with a very specific target audience and demographic, they have far greater potential for traffic generation than ads selected simply through cookie and browser history. Additionally, some of these websites have also implemented measures to make ads more relevant to users by allowing users to vote on which ones will be shown on pages they frequent. The ability to redirect large volumes of web traffic and target specific, relevant audiences makes social bookmarking sites a valuable asset for social media marketers.
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. Wired magazine reported that the same company sued blogger and SEO Aaron Wall for writing about the ban. Google's Matt Cutts later confirmed that Google did in fact ban Traffic Power and some of its clients.
Early versions of search algorithms relied on webmaster-provided information such as the keyword meta tag or index files in engines like ALIWEB. Meta tags provide a guide to each page's content. Using metadata to index pages was found to be less than reliable, however, because the webmaster's choice of keywords in the meta tag could potentially be an inaccurate representation of the site's actual content. Inaccurate, incomplete, and inconsistent data in meta tags could and did cause pages to rank for irrelevant searches.[dubious – discuss] Web content providers also manipulated some attributes within the HTML source of a page in an attempt to rank well in search engines. By 1997, search engine designers recognized that webmasters were making efforts to rank well in their search engine, and that some webmasters were even manipulating their rankings in search results by stuffing pages with excessive or irrelevant keywords. Early search engines, such as Altavista and Infoseek, adjusted their algorithms to prevent webmasters from manipulating rankings.