As you walk through an office with your laptop or phone, you come within range of different access points. Roaming is the process of switching from one to the next.
If it works well, you do not notice a thing. If it works badly, your video call drops as soon as you walk from your desk to the meeting room. Or your device stays connected to a distant access point with a weak signal, while a closer one is available.
Good roaming requires a well-configured network in which the access points are configured to work together.
What does this mean for the IT-Label?
Roaming is part of how well the WiFi network works, and therefore falls under Infrastructure and Performance. The audit measures where people work and move around. In logistics buildings, where scanners and vehicles move through the warehouse, good roaming is especially important. See also access point and WiFi survey.