Considered a form of interruption marketing, interstitials are any page or pop-up that forms a roadblock to users’ path to content, either by displaying over the content or interrupting it. Users have no choice but to interact with the display before they can proceed. Forbes was a classic example of the “before” interstitial (also known as a “prestitial”).
Some ad platforms will ask more of your landing pages than others, when running ads. For example, AdWords is much stricter, when compared to Facebook. AdWords typically requires that you do not have a ‘thin,’ site that is designed solely to collect leads. Because of this it might be a good idea to focus on using Facebook or Twitter, to begin with.