Can you buy Wi-Fi by itself?

Excuse me, I'm a bit confused about something. I was wondering, is it possible to purchase Wi-Fi on its own, without having to buy a router or any other hardware? I've heard some people talk about buying Wi-Fi plans, but I'm not sure if that's what they actually mean. Could you please clarify this for me? I'm just trying to understand the basics of how Wi-Fi works and what I need to get started. Thank you in advance for your help.