You can organize devices provisioned in one environment into groups to target them in campaigns. Each provisioned device can be targeted in different groups, but you cannot target devices from different environments in one group. For more information, see What is an environment.
There are two types of device groups:
The fixed group type is useful if you already have a fixed list of devices that you want to update.
The smart group type is useful if you know the selection criteria for devices that you want to update but do not yet have a fixed list of devices.
Even if you do have a fixed list of devices, smart groups can also come in handy when you constantly add new devices to your list. Smart groups automatically group newly provisioned devices that match certain selection criteria.