A search engine is a website or part of a website that allows you to search either the entire Internet, or a given website for specific information.
Google, Yahoo, Excite and Dogpile are just a few of the common search engines that search the entire Internet for information on any word or topic you type into their search box.
As you may well imagine, it is not an easy thing to create software that searches the entire Internet with accuracy. Rest assured, it is even tougher to find people to design such software for free.
Google, Yahoo, AskJeeves, Excite, and every other search engine requires money to stay afloat.
How do companies like these, that provide a free service, stay in business. The answer is almost always the same – Advertising.
When you type a word or phrase into Google or any other search engine, the first few results are typically from companies that have paid to show up as one of the first results. Typically these sites are marked as paid ads, but not always.
This isn’t to say not to click on the paid ads in search results, but it is important to realize that the first few results are not necessarily there because they are the most popular or even the best results for what you were searching for.
Follow this link for an example of how Google uses advertising. Notice the top two results say "Sponsored Links" at the far left. Also in the far left is an entire column of advertisements.
Notice the "Sponsored Links" text above. This is an obvious indicator that you are looking at a Google Ad.
Yahoo looks almost identical, except for the term "SPONSORED RESULTS"- see below.