Wi-Fi Assist is a feature in the iPhone to help with internet connections.
The name is a little misleading, though as reader Bob Andres finds out:
Does Wi-Fi Assist boost cell phone reception in a low-service area??
We have poor service in our stone office building and are hoping Wi-Fi Assist will make the difference.
If you’re on a Wi-Fi network and access is spotty, iOS will “assist Wi-Fi” by tapping into an accessible cellular network.
(And, warning, a lot of people in the past have sucked down massive amounts of data unintentionally by enabling this feature, which Apple has turned on by default.