Found this info on Wikipedia: Tethering means sharing the Internet connection of an Internet-capable mobile phone with other devices. This sharing can be offered over a wireless LAN (Wi-Fi), Bluetooth, or by physical connection using a cable. In the case of tethering over wireless LAN, the feature may be branded as a mobile hotspot. The Internet-connected mobile phone acts as a portable router when providing tethering services to others. Many mobile phones are equipped with software to offer tethered Internet access. The operating systems Windows Phone 7 (built-in starting from version 7.5 Mango), Android, (starting from version 2.2 Froyo), and iOS (only after jailbreak or running iOS 4.3 or higher on iPhone 4 or iPhone 4s without jailbreak) support this. This feature, on the devices bonded to some operators, was available before, but now this feature has been disabled and can be reenabled only by 'rooting' devices and using the Linux iptables application. Android devices offer tethered Internet access even with the latest version, Android Ice Cream Sandwich. Some operators however asked Google or any mobile producer using Android to remove this service.  Tethering is available as a downloadable "wifi hotspot" application on most Symbian mobile phones  as well as on the MeeGo platform.  I love my tmobile service because they don't charge me for doing this. I hardly ever need to because I'm around wifi at most places I use my iPad.