PPC is a relatively simple concept, and if you can get it down to a fine art there is considerable money that can be made.

In its simplest form you pay money to get clicks through to your website. Mostly though web marketers do this with the intention of converting a certain percentage of the visitors into a sale, and this is how money is made.

I will give you an example, lets say you are selling sun glasses and you want to target Canadians. You could set up a PPC campaign with a company like Google Adwords and target Canadians that were searching for words like "Buy Sunglasses" and depending on the competition you would pay a certain amount per click.

Once you create a stream of traffic to your site you would probably find that a certain percentage would actually buy the product and this is called the conversion rate. If you are making more than what you are spending on PPC then you are doing well.

Of course PPC is not always done for those looking to make a quick sale, sometimes webmasters just use it to get general traffic to their site.

I found a great site that has some more information on PPC, particularly PPC tools which you would be wise to look at if you are interested in getting into PPC yourself.