Detention and demurrage are two related charges that can be assessed by shipping companies for the use of their containers.

Detention refers to the payment that is charged to a client for the use of a shipping container outside the free period after it has left the terminal. This charge is typically assessed on a per-day or per-hour basis, and is meant to compensate the shipping company for the cost of having the container tied up and not in use.

Demurrage, on the other hand, refers to the payment that is charged for the use of a shipping container while it is still at the terminal outside the free period. Like detention, demurrage is typically assessed on a per-day or per-hour basis, and is meant to compensate the shipping company for the cost of having the container tied up and not in use.

Both detention and demurrage can be significant costs for shippers, particularly if they are unable to return the container to the shipping company in a timely manner. As a result, shippers may try to minimize these charges by carefully planning their logistics and ensuring that containers are returned to the shipping company as soon as possible.