Sharing the phone's data with a laptop or another device. Some plans cap it.
Tethering turns the phone into a Wi-Fi access point for other devices. It is allowed on many travel eSIMs, but some plans cap it, for example at a fixed number of GB per day, and some block it.
Laptop work uses much more data than phone use, so the cap matters most for people who work on the road.
What to check
- Check the hotspot rule before you buy an unlimited plan
- Count laptop use separately when you size a fixed plan