Mobile advertising and interaction surpassed Desktop and Tablet beginning in late 2015. Targeting these devices is still a prerequisite to any campaign especially retail, finance, lawyers, dealerships, and healthcare.  Predefined Audience Lists are designed to isolate people into categories which are usable for locating personal devices with intent to purchase an automobile, home, healthcare options, insurance, home improvement, and other retail or services. Going a step further, Custom Audience Lists can be created prior to starting a campaign. CAL’s are defined by demographic and needs based data for a specific area. This is the same as a re-targeting list that campaigns use to catalog their new click activity. The difference is the CAL is built before their use instead of after daily activity. And Yes, there is a cost to produce this list. Some feel the need to have a predetermined list rather than a list of results.