In the jargon-filled world of online advertising, CPA -- cost-per-action -- advertising may seem confusing at first. Also known as "pay for performance," CPA is an effective way for advertisers to select how they want to pay for their advertising -- by click, impression, sale, or other variable.

Pay-for-click advertising is very popular, but it can be costly. As such, it may be out of reach for many businesses. If you prefer to pay by sale, CPA-based advertising can deliver your customers to you and guarantee that you won't pay a dime unless until you make a sale. In the highly competitive and expensive world of Internet advertising, this is a rare bit of insurance for your company’s advertising budget.

But sales aren't the only "actions" you can choose to pay for. If you offer registrations or subscriptions on your site, a CPA-based program can be very effective. If you are simply seeking new leads for your company by using an opt-in mailing list, you can utilize CPA-based advertising to guarantee interested leads.