Which network is public?

I'm curious to know, which network out of the many in the cryptocurrency and finance world is considered public? By public, I mean one that is open and accessible to anyone, without any restrictions or permissions required to participate. Are we talking about a blockchain network that allows for transparency, allowing users to see transactions and activity on the network? Or perhaps a decentralized finance (DeFi) platform that promotes openness and inclusivity? I'm eager to learn more about the specifics of a public network in this context.