A more thorough explanation:

Definition: An accessorial obligation is a liability that a person takes on when they become responsible for someone else's debt. It is also known as a collateral obligation.

Example: If a person co-signs a loan for their friend, they are taking on an accessorial obligation. If their friend fails to make payments on the loan, the co-signer is responsible for paying it back.

Explanation: The example illustrates how a person can become responsible for someone else's debt and take on an accessorial obligation. In this case, the co-signer is not the primary borrower, but they are still responsible for the debt if the primary borrower defaults. This is a common example of an accessorial obligation.