Abstract: A computer-implemented method, apparatus and product for impression time units based online advertisement. The computer-implemented method, being performed by a processor or similar computerized device, comprising: having a placement opportunity to be fulfilled; obtaining a plurality of potential advertisements for the placement opportunity, wherein each potential advertisement is associated with at least a proposed impression time unit charge rate and a requested impression time unit allocation; and matching an advertisement from the plurality of potential advertisements to the placement opportunity based on the proposed impression time unit charge rates and requested impression time unit allocations.

Abstract: A method, system and product useful for online advertisement. The method comprising: displaying a first advertisement in a web page, wherein the first advertisement is associated with a compensation model that is contingent on a user action by a user with the first advertisement; and replacing the first advertisement by a second advertisement that is associated with a serving-based compensation model. In some embodiments, the first advertisement is replaced in response to a determination that a probability that the user action will be performed by the user is below a predetermined threshold. In some embodiments, the first advertisement is replaced in response to a determination that a predetermined threshold time has elapsed after said displaying the first advertisement. In some embodiments, the predetermined threshold time is computed for an ad impression relating to the first advertisement, to the user and to the web page.