How does Ethereum discover nodes?

How exactly does Ethereum discover other nodes in a decentralized fashion? I am quite familiar with many of the concepts that build Ethereum but I can't quite understand how the particular function happens?

From my networking knowledge, this would be a process similar to DNS though that is centralized. Is it at all similar?

I know this is likely documented somewhere so if anybody has a link I would be eternally grateful!

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Note:

by Nodes I currently mean the PoW nodes that validate the chain but I would also love to know about this process and/or if it changes in the PoS system.