What is hash key for password?

Could you please elaborate on what a hash key for a password is? I understand that it's related to cryptography and security, but I'm not entirely clear on how it works or why it's important. Is it a unique identifier for a password that's used to verify its authenticity? Or is it a way to encrypt a password so that it can't be easily accessed by unauthorized users? I'd appreciate it if you could provide a clear and concise explanation of the concept and its significance in the world of cryptocurrency and finance.