Account sharing
Account sharing is when two or more people share the same account by sharing their username and password with others. For example, someone may share their Netflix account information with friends and family, so they don't have to pay for the service. In a computer game, someone may share their account to allow their friends to play a game or give themselves an unfair advantage against other players.
Why is account sharing a bad idea?
Sharing your account details allows anyone with that information to do anything, which means they could take control of the account or delete it.
If someone else is logged in to your account, it may prevent you from using that account because someone else is already using it.
Finally, account sharing is often against a platform's TOS (Terms Of Service) and if caught, could cause your account to be banned. For example, in early 2022, Netflix announced they are cracking down on subscribers that share their account with other people. The company stated they would charge users an extra monthly fee to continue sharing their account.
Is account sharing with games cheating?
Yes. Sharing your account with others gives your player an unfair advantage because it's easier for multiple people to advance a character in a game than one person. For example, one person could use the account and play the game while the other person is sleeping. The first person could then go to sleep and the second person plays the game with that account.
If you're sharing an account with other people who have a different character, it may not be considered cheating, but may still be against the games TOS.