What occurs each time an ad is displayed?Landing pageImpressionClickCost-per-Click

Each time an ad is displayed, an "Impression" occurs. This term is used in online advertising to represent the display of an advertisement to a user on an internet page. It's a way to measure the number of views a particular piece of content receives. The other terms mentioned - Landing page, Click, Cost-per-Click - are also related to online advertising, but they represent different aspects:

1. Landing Page: This is the webpage where a visitor ends up after they click on an ad. It's where the user "lands" after being directed from the ad.

2. Click: This refers to the action a user takes to click on an ad. This is another metric used in online advertising to measure engagement.

3. Cost-per-Click: This is a pricing model used in online advertising where an advertiser pays a publisher every time an ad is clicked.