Non-intentional traffic (NIT) is visits to publishers which occur without the knowledge of a user, or driven by non-human actors. It can be initiated by human actions, or fully controlled by a bot that has infected a personal computer. There are two primary types of NIT. In one, users are automatically redirected to particular websites after closing another website. In the other, content (ads and/or full websites) invisibly load in the background (often in a 1x1 pixel) while a user is intentionally viewing content from other sites. This traffic pollutes the display advertising ecosystem and thwarts most efforts to accurately measure the medium for effectiveness.
The perpetrators of NIT generally have two main objectives. First, to generate huge volumes of pageviews, producing ad inventory they can sell on advertising exchanges. Second, botnets produce their own "conversion" events by simulating clicks on those invisible ads and/or hijacking the infected browser to record a "visit" to the sites of marketers whose ads have been invisibly run, sometimes going so far as to produce a "lead" (e.g., a visit to a store locator page). The effect is to increase the perceived value of those infected browser to both marketers and targeters.