Hi, title says it all but I'm trying to understand the difference between 2G and 3G.

From what I can make out by reading various posts here, 3G signal appears pretty poor on most networks. So if I set my phone to 2G/GSM only will I still be able to get fast internet and/or wi-fi, or would I have to switch the network back to 3G for that?

I'm on O2 in London if that helps at all.

Apologies if its a bit of a dumb question.
Cheers.

The data rates on 3G are higher than 2G so although you can do Internet on 2G it will be a pretty slow experience. 3G would certainly be the better option if you have the choice.

Though 3G coverage does not quite match 2G in many places.

WiFi is nothing to do with 2 or 3G. You can theoretically have WiFi access with no mobile phone signal at all. What you do need is either a wireless broadband router or a public WiFi access point where you are.