Using your phone to connect a laptop or tablet to the internet is called tethering.
It's a bit like using mobile broadband, but instead of a dongle you connect your phone to a laptop or WiFi tablet using Bluetooth, a USB cable, or portable WiFi hotspot.
You can only tether on some 3G and 4G devices, such as Android phones and iPhones.
How to tether via WiFi, USB or Bluetooth
How much does tethering cost?
Tethering is included in your plan as part of your data allowance.
The plan you purchased will have a data allowance which you can use to access the internet on your phone, use apps on your phone or use your phone as a portable hotspot to tether.