Are all iPhones 3G or are there Wi-Fi ones and 3G ones?

I'm thinking of buying a second hand iPhone, but would I be an idiot for asking if its 3G or not? Are all iPhones built in with 3G? Or do you have to pay extra? Also are the samsung galaxy note and the samsung s3 3G aswell?

I know from version 3GS and later they are all 3G, unless you are talking about something way older then that like the first iphone release ever but I doubt thats what you are looking at. As far Wi-Fi only, no, as thats like an ipod touch which is only Wi-Fi, not phones.

The original iPhone was not 3G enabled but all the rest are. All iPhones are Wi-Fi enabled.
The iPhone 5 is the 1st & only 4G enabled iPhone (for now)

Yes both the Galaxy Note & S3 are 3G phones.

I don't have an Iphone but I'm sure most Smartphones that have 3G enabled also have WI-FI as well.