An Advar template always consists of two files:
The creative's actual content that contains parameters that refer to the properties of an uploaded creative and its files. Besides any custom parameter defined by the creator of the Advar template, the creative content can also contain a number of fixed parameters.
A descriptive file that is used to generate the form that will be presented to a user when uploading a creative. This file contains a JSON object that defines the different elements available in the template. It will determine how the form is rendered to the user.
As with templates, an Advar template can also contain a request element as a parameter. All request properties can be used as content in an Advar template. For example, the creative can display the name of the visitor if this parameter is added to the call to the ad server (and if the value of the name is available, of course).