Pay Per Click or PPC is paid advertising in Search Engines. Advertisers pay the Search Engine each time a searcher clicks on their displayed advertisement or sponsored link.

Using a system of bidding provided by each Search Engine, the advertisers can choose to have ads listed higher or lower for a keyword, depending upon how much they are willing to spend per click and the amount of traffic they want. Higher the paid listing on the search engine result pages (SERP), higher is the Cost-Per-Click.
PPC – an Effective Search Engine Marketing Vehicle
PPC as a marketing vehicle has certain unique features, no other form of online promotion can match:

• Definite: PPC is instant form of marketing, specific countries; cities and languages can be targeted.
• Controlled Cost and Traffic: The definite nature of PPC allows traffic and cost to be controlled to exact figures as per business models, budgets, sales handling, and growth plans.
• Flexible: Changes can be made to the campaign depending on the current business needs instantly.
• Low Risk: PPC is not Search Engine Algorithm dependent and is guarded against any changes that might happen in Search Engine Algorithms.

In short, PPC programs let you choose the keywords you want to advertise on, the amount you want to spend per click, the message you want to send out, the cities/countries/languages you want to target and you only pay if you get visitors!