What exactly is 3G and why is it more expansive than WiFi?

I have a iPhone 3GS and have very good WiFi networks at work and home. I am wondering if I should keep WiFi on while I am at one of these locations. Between WiFi and 3G, what consumes less battery?

I'm in an apt that is not hooked up to cable (believe it or not, in this day and age!), nor is there a phone jack to use DSL. I'm not interested in getting cable, nor even their internet access only plans. I just want internet use on my laptop &...

I know this is a common question, but I'm not keen on this stuff, and I don't quite understand other answers. I know that WiFi is just a wireless internet connection that you need to be in a hotspot to get. But I don't know what 3G and 4G are, or how...

What cool things can I do with a spare, jailbroken iphone 3g? (wifi service only) Greetings, I have an iphone 4 and an ipad (3G) thus I have the standard uses covered. I also have a spare iphone 3G that I have jailbroken. Being as my other ios devices...

Okay, so I'm planning to buy an iPad and would like to know more of the details. I know that ipad wifi + 3g would offer me with internet usage anywhere and anytime. However, is it true that the ipad wifi + 3g is faster than the normal iPad? If so, how...

I understand that buying a WIFI tablet would enable me to surf the web by just picking up local (like... 30 meters) wifi internet that I already have in my apartment. So what exactly do I benefit by adding the extra $$$ and buying a Galaxy or an Ipad...

I am going to get the new ipad 2 but i wanted to know the difference between the wifi+3g model and the model with just the wifi

Clearly it sounds like I have answered my own question, what I mean is the specifications of the machine itself. Are they the same besides the 3G in one reather then both, or is the 3G more powerful?