Do ads recognize if they are visible or not?

Do ads on webpages recognize if they are visible? So does the website owner get money also if the ad is not visible?

I think about situations where the page is not adapted for mobile devices and the whole page is not visible at once. Although the user could scroll to the ad section and see the ad.
Does the webpage owner still get payed in that instance?

Related to your question regarding "viewability"... Ad viewability is a measure used to determine whether an ad had the opportunity to be seen by a user. For example, the Media Rating Council (MRC) and the Interactive Advertising Bureau (IAB) define a viewable display ad impression as one where at least 50% of the ad's pixels are in view for a minimum of one continuous second.

Modern ad technologies (like Google's Active View) can track viewability by observing where the ad is placed on the webpage, how long the ad was on the screen, whether the user was focused on the tab where the ad appeared, and other factors. If an ad is placed in a location that users typically scroll past before the ad loads, or outside of the visible screen area, it might not count as a viewable impression, and that may affect how much the website owner is paid for that ad.

So, in your scenario, where the ad is not immediately visible on a mobile device but could be visible after scrolling, the ad may or may not be considered "viewable" depending on how long the user keeps it on the screen and other factors. If the website owner is paid based on ad viewability or interaction (clicks or views), the payment may be impacted. However, if they are paid per impression, the ad loading onto the webpage, even if not immediately visible, would likely still generate revenue.