Most major search engines display a combination of organic and paid search results when answering users' queries.
The organic are the main results — often labeled "Web Results" or something similar. Paid listings are displayed separately on search result pages and generally listed as "Sponsored" results.
The organic search results returned by a search engine for a given search keyword are generated through intricate ranking calculations that determine the relative relevance of the Web pages listed in the search engine's index in relation to the entered keywords along with a multitude of other factors. These organic results are the "true" output of the calculations that comprise a search engine's ranking algorithm. A high organic search engine ranking can only be attained through effective search engine optimization (SEO). Occasionally, certain Websites automatically rank highly for very particular, non-competitive keywords.
Paid search engine advertising offers an alternative or companion to positioning a Website for organic search engine listings. Most paid search engine advertising is built around the so-called pay-per-click (PPC) concept. Simply put, PPC allows advertisers (i.e., Website/business owners) to bid for the top ranking for a given keyword. The advertiser that places the highest bid is ensured the top ranking for that keyword until he/she is outbid. The second-highest bid is secured the number 2 ranking; the third-highest bid claims the 3rd spot, etc.
If you are willing to pay for it — and perhaps even engage yourself in bidding wars with other advertisers — PPC can be an enticing option. Many large-scale e-businesses rely on a combination of paid advertising and targeted SEO.