An online ad placement is generally characterized by its location, whether on a website, a specific page, or a particular type of page, as well as its size, expressed in pixels. For example, the 300 x 250 pixel rectangular format found on the MSN homepage or the skyscraper visible on the “definition” pages of the same site are examples of ad placements. Each ad placement is associated with an advertising tag generated by the ad server and then inserted into the page at the desired location.

When planning an advertising campaign, the ad server selects the placements or groups of placements where the ad creatives will be displayed. Because managing online advertising campaigns is entirely dynamic, the same ad placement can be shared between several campaigns and different creatives during the same period, depending on the specific criteria of each campaign, such as targeting, volume, frequency capping, etc. This is why it is possible to see different ads each time you visit the same page multiple times.

Below is an example of advertising placements available on a web page. The source image is from Mediakit Fact Monster.