You already know Steem's private keys. But here is a brief analogy to remember what the key is, what and how it should be secured.
Publish a private key
This key is for your home, where anyone with access to your keys can enter your house, use your common things on your behalf because you have a certain level of trust. In a Steem case, Vote, Comment, Publish, Reputation
Active private key
This key is for your safety / security where you keep your money, not many people know the password but only you. Anyone who has access to this key can control everything in that vault, in addition to their identity. In a Steem case, check your balances and funds, account details
Owner's private key
This key is the key to your home and insurance / safe, as well as access or permission to completely own the home. In a Steem case, ownership of the account
Memory Key
This key is your signature where you sign the document or important messages / mails. In a case of Steem, encrypt messages, private communication.
You can share any of the above authorizations with other Steem accounts.
Like, you can rent a room in your house or have more than one password to access the safe or common property of the property / home or appoint a lawyer.
conclusion
Always know how your private keys are used and who has access to them. Use with caution!
Better be sorry or make a related analogy, be careful, do not kill the neighbors! :)
Steem on!