Can you make your own Wi-Fi without a provider?

Excuse me, I'm curious to know if it's possible to set up my own Wi-Fi network without relying on an internet service provider? I've heard of some DIY solutions that allow individuals to create their own networks, but I'm not entirely sure how it works or if it's feasible. Could you elaborate on the process and any potential limitations or challenges that come with creating a standalone Wi-Fi network? It would be great if you could provide some insights into the necessary equipment, costs, and security considerations that need to be taken into account.