This app monitors the phone USB port. Whenever the phone is connected to a computer or laptop via a USB cable the app automatically turns on USB tethering, optionally after confirmation by the user. USB tethering is available since Android version 2.2 but it takes quite a few annoying taps on the phone screen to turn the feature on. Auto USB Tethering automates all these manual steps. Just connect the phone to your laptop and you are instantantly connected to the Internet from the laptop over 3G/4G network.
This is handy if you often use your phone as a modem to provide your laptop with Internet connection for a longer period of time. WiFi tethering is suboptimal for such a use case. Since WiFi tethering drains battery very fast, you would need to put the phone on a charger one way or another (AC or USB) and USB connection is way faster and more reliable then WiFi.
USB tethering works well with all recent versions of Windows and Linux. It does not work with Mac OS without 3rd party driver. The developer website has for more info about this app including a FAQ.
There is also "Auto USB Tethering Premium" which provides more configurability. Please check it out if you think this app is useful and plan to keep it installed.
ATTENTION: Devices distributed by some operators (AT&T?) have modified version of Android installed which disables the standard USB tethering capability. This app will not work on those devices. Please don't give the app bad rating because of that. Blame your operator instead. To fix it you either have to "root" the phone and install a different firmware (ROM) or switch to a different device. There is nothing this app (or any other ones) can do.
Updated the app manifest to disallow installation on unsupported Android versions