The Audience Targeting section can be found at the bottom of any campaign. This is where you can define the audience that will be seeing your ads. The first tab you will see open is Technology and advertisers are able to specify whether they want to target Desktop/Mobile, by Manufacturers, by Operating Systems and more.
By default, All is selected for every filter option.
Internet Carriers such as AT&T or Verizon.
If the user is on Wi-Fi or on their Cellular Network
If the user is on desktop or mobile.
Manufacturers of desktops and mobile devices such as Dell or Samsung.
The operating system that is in use such as Windows, iOS or Android.