Tethering means making your internet-connected phone into a wifi hotspot, so other devices such as you Laptop or Ipad, can share the connection. It's way to share your phone's internet connection with your other devices.
If you want to do this, it's usually best to make sure that you have an unlimited Internet plan on your phone. I have two phones, one on ATT and one on TMoblie. The Tmobile one has unlimited internet, so that's the one to use for tethering.
Despite the outlandish claims made by cell phone companies, their internet is really slow. I have an iphone running on t AT&T and it's slower than an old 14.4 modem. I don't care what their TV ads say about lightening fast service. If you are used to a fast DSL connection you're going to hate what the cell phone gives you. On the other hand, it's great to not have to worry about finding a hotspot if you want to get online.
ATT supports tethering, but at last check, they charged an extra ten dollars a month, plus you have to pay bandwidth charges. The best solution is to switch to an unmetered data plan such as Tmobile so you don't have to worry about the charges..
For Tethering software you have several choices.
There is an APP store app called "Itether" that you can download for $15. This will allow you to do tetherning without going through AT&, but this is very recent (December 2011) and was banned up until now. PC world has an interesting article about it.
Att doesnt like this
http://osxdaily.com/2011/03/17/att-cracking-down-on-unofficial-iphone-tethering-mywi-users/
Here's how to get it going
http://osxdaily.com/2010/12/19/iphone-wifi-hotspot/
Basically you go to Cydia and download the app. It cost $19.99
The program runs in the background on your phone. I turned on the wifi hotspot and bluetooth features.
Using MIFI Iphone Hotspot
Once the software is installed, you need to configure it.
I usually use the