An older form of advertising that is known as PI (per inquiry advertising) has been replaced in the online world as something similar that is called CPL (cost per lead). In years past, PI would be used where businesses would get to run ads free across many different mediums like TV, radio, print, billboards, etc. The business advertising would only pay when they recieved responses from the advertisement. The details on what is considered a quality response are decided on beforehand between the company advertising and the people running the ad. The PI model can be used online, but it mostly been overtaken by a rehashed version in CPL and PPC (pay per click).
The techniques involved with SEM (search engine marketing) and SEO (search engine optimization) allow you to utilize CPL to increase your lead generation. With the cost per lead method, pretty much the same thing happens. Another website will host an ad for your site, for free, and you only pay if someone clicks the link and generates a lead for you. The lead generation is very important here, as it marks a key difference between CPL and PPC (pay per click) advertising. With PPC, you pay the site anytime someone clicks the link on their site to come to yours. It doesn’t matter if they do anything after that or not. You still pay anyways.
With CPL, the visitor must not just click the link, but also generate a lead. That means they need do something that will help you generate a potential sale. They might have to fill out a marketing survey or sign up for a newsletter. The newsletter is usually what most people accept as the terms for this type of advertising. If you can get someone’s email address, you can always follow up with them and try to land a sale later one.
In order for PI advertising to work correctly, it needs to be able to be tracked, so that the advertiser knows exactly who is responding to his ad. With CPL, you can see exactly what site the user came from and you can see if they signed up for anything. Thus you know exactly which hosting sites to pay and which ones not to pay. Another benefit of CPL is that you can use SEM and SEO to help increase traffic to your site.