Social media can be used not only as public relations and direct marketing tools but also as communication channels targeting very specific audiences with social media influencers and social media personalities and as effective customer engagement tools. Technologies predating social media, such as broadcast TV and newspapers can also provide advertisers with a fairly targeted audience, given that an ad placed during a sports game broadcast or in the sports section of a newspaper is likely to be read by sports fans. However, social media websites can target niche markets even more precisely. Using digital tools such as Google Adsense, advertisers can target their ads to very specific demographics, such as people who are interested in social entrepreneurship, political activism associated with a particular political party, or video gaming. Google Adsense does this by looking for keywords in social media user's online posts and comments. It would be hard for a TV station or paper-based newspaper to provide ads that are this targeted (though not impossible, as can be seen with "special issue" sections on niche issues, which newspapers can use to sell targeted ads).
Webmasters and content providers began optimizing websites for search engines in the mid-1990s, as the first search engines were cataloging the early Web. Initially, all webmasters only needed to submit the address of a page, or URL, to the various engines which would send a "spider" to "crawl" that page, extract links to other pages from it, and return information found on the page to be indexed. The process involves a search engine spider downloading a page and storing it on the search engine's own server. A second program, known as an indexer, extracts information about the page, such as the words it contains, where they are located, and any weight for specific words, as well as all links the page contains. All of this information is then placed into a scheduler for crawling at a later date.