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.
If you are using Responsive Web Design, use meta name="viewport" tag to tell the browser how to adjust the content. If you use Dynamic Serving, use the Vary HTTP header to signal your changes depending on the user-agent. If you are using separate URLs, signal the relationship between two URLs by tag with rel="canonical" and rel="alternate" elements.
The fee structure is both a filter against superfluous submissions and a revenue generator. Typically, the fee covers an annual subscription for one webpage, which will automatically be catalogued on a regular basis. However, some companies are experimenting with non-subscription based fee structures where purchased listings are displayed permanently. A per-click fee may also apply. Each search engine is different. Some sites allow only paid inclusion, although these have had little success. More frequently, many search engines, like Yahoo!, mix paid inclusion (per-page and per-click fee) with results from web crawling. Others, like Google (and as of 2006, Ask.com), do not let webmasters pay to be in their search engine listing (advertisements are shown separately and labeled as such).
There are many reasons explaining why advertisers choose the SEM strategy. First, creating a SEM account is easy and can build traffic quickly based on the degree of competition. The shopper who uses the search engine to find information tends to trust and focus on the links showed in the results pages. However, a large number of online sellers do not buy search engine optimization to obtain higher ranking lists of search results, but prefer paid links. A growing number of online publishers are allowing search engines such as Google to crawl content on their pages and place relevant ads on it. From an online seller's point of view, this is an extension of the payment settlement and an additional incentive to invest in paid advertising projects. Therefore, it is virtually impossible for advertisers with limited budgets to maintain the highest rankings in the increasingly competitive search market.
In 1998, two graduate students at Stanford University, Larry Page and Sergey Brin, developed "Backrub", a search engine that relied on a mathematical algorithm to rate the prominence of web pages. The number calculated by the algorithm, PageRank, is a function of the quantity and strength of inbound links. PageRank estimates the likelihood that a given page will be reached by a web user who randomly surfs the web, and follows links from one page to another. In effect, this means that some links are stronger than others, as a higher PageRank page is more likely to be reached by the random web surfer.