Search Engines have evolved from simple information gathering machines into giant income producing machines. They continue to perform the search and share function but have added advertising extensively. Google, Yahoo, and Ask.com all use Adwords as their main source of income. Each and every time someone uses these search engines they receive their search results but are also shown "paid for" advertising slightly masked as legitimate search results. The "paid for" advertising is usually in a column on the right side of the screen and occasionally in a colored box just on top of the legitimate search results. These are called "Adword" advertisements because they are based and directed by the original search term (words) the Google user typed in.
Additionally, these advertisements are also placed on many other types of websites based on the websites content not any search terms. The content website owners share the advertising income with Google. More...........