Useful when switching devices or accounts
Logging out is worth knowing when you're handing a device to someone else, or need to sign into a different account temporarily -- it is a routine, reversible action, not something to be cautious about the way deleting an account is.
Do not confuse it with deleting your account
Logging out keeps your account and data intact for whenever you sign back in. Deleting an account is a separate, much more permanent action that erases your message history and account entirely -- the two shouldn't be confused.
Frequently Asked Questions
Will I lose my chat history if I log out?
No, for an app that stores your history on its servers -- logging back in restores your conversations as they were. For an app that relies on local device backups instead, it is worth backing up first just in case.
What do I need to log back in afterward?
Usually the phone number or account credentials used at signup, plus a verification code sent to confirm it is really you.