What is a break-glass account?

A break-glass account is a rarely used administrator account kept aside for the day the normal way in fails:

• It belongs to the business, not a person - so it survives someone leaving, or being unreachable.
• Its credentials live offline - written down, sealed, stored physically. Not in the system it would rescue.
• It is not used day to day - which is what keeps it clean, and what makes any use of it worth investigating.

For a small business this is one extra administrator account in Microsoft 365 or Google Workspace, and an envelope.