What is meaning of Demurrage for ships ?

Monies paid by the Charterer to the owner of the ship for delays in loading and unloading in accord with the terms of the Charter Party.

The rate of demurrage is fixed and agreed between the owner and Charterer at the time of completing the Charter Party and cannot be altered. Can be taken in contrast with ‘Despatch Money’ opposite to demurrage where the ownerm pays reward money to the Charterer for completing loading and/or discharging earlier than the expiry of ‘Laytime’.