Basically dominated the AdServer:
Normal Banner, so graphic files as GIF, JPG, PNG, WebP or SWF
HTML banners, so ultimately any HTML code
Popups Popunder, (DHTML) Layer
Banner can thereby be created in 3 ways:
The banner is already on a server (eg the customer) and is only inserted.
Several banners were already loaded onto a (customer) server and are all added together using a CSV file.
One or more banners are available as file and are automatically uploaded and added automatically.
As a rule, Option 3 is used here as a campaign usually consists of several advertising media, which are delivered directly from the customer. This also has the advantage that it can be ensured that the banner can be displayed with sufficient speed.
An HTML advertising media is nothing more than a normal HTML code that is usually prepared accordingly so that you can click on it and go to the advertised website. In addition, HTML advertising media are in particular always used when campaigns are used by different manufacturers AdServer (ie from marketers A passes a campaign to marketers B, but both want to count clicks and views).
Popups / pop / Layer
Besides banners and HTML advertising pop-ups play a special role. A distinction is made between popups (window in the foreground), Popunder (window in the background), and Layer (window within the page itself) and again between normal popups / pop, which are opened when the page and those that open when leaving the page (so-called ExitUps). Usually pop-ups and pop are used in conjunction with an alternatively-Layer: If the pop-up / pop prevented by a popup blocker, instead of the layer is displayed. This makes the advertising reach and thus the yield is massively increased, since now many visitors use such blockers.
Content of such advertising means an ordinary HTML code can be either (that ultimately everything a normal home page also will bear) or it can be an external URL (usually the customer's website) are loaded and displayed in the popup.