This is the total ad space that you have available for sale on your website for advertisers to display their ads on. A simple way to think of it is Number of Ad Units per Page * Total Number of Pages

Any individual slot where ads can do. Ad units come in multiple sizes and can be placed in many locations across the websites. All the ad units combined make up for your ad inventory.

The International Advertising Bureau is an industry body that defines universal ad sizes to maintain uniformity in ads displayed across the web. A list of the most common IAB ad sizes can be found her [..]

Alternatively known as a “campaign”, an order is an ad request placed by an advertiser on a publisher’s website. It can be an ongoing or time-bound activity and include multiple ad sizes.

Every order as described above must include at least one line item, which defines the ad to run, which unit it will run in, which creative to use, and details about any custom targeting.

The actual ad that will run in a line item. This can be an image or Flash file, or a pointer to an ad code from an ad network connected to DFP.

Targeting involves the intentional limiting of the audience an ad is displayed to, for instance, you may want to display your ads only to English speaking users on a broadband connection in a specific [..]

Any intelligent grouping of ad units can be thought of as placements, for instance, all Skyscraper units on a particular website or all ads on a particular content category or tag — placements are use [..]

DFP continously monitors your site’s traffic and impressions already reserved by exiting line items to predict the future availability of your ad inventory. This is helpful in two ways: During the sal [..]

Frees up inventory that has been reserved by a line item. For instance, let’s say that a line item was guaranteed to serve 20,000 impressions but you need to stop the order after 10,000, releasing inv [..]