Can my iPhone just use Wi-Fi without a phone service?

Like say I buy a verizon iPhone on craigslist, but not pay for phone service… Can I still use the iphone with Wi-Fi only?

Yes you can I do that now

Do people not know what an iPod Touch is?
It's basically an iPhone without cellular connection. Just get that. It's way cheaper and starts at 32GB (and thinner and lighter as a bonus)

Yeah you can. You'll just get bugged by "No SIM installed" messages… Depending on the iPhone, it'd be cheaper to get an iTouch.