A money order is a payment order for a pre-specified amount of money. As it is required that the funds be prepaid for the amount shown on it, it is a more trusted method of payment than a cheque.
The money order system was established by a private firm in Great Britain in 1792 and was expensive and not very successful. Around 1836 it was sold to another private firm which lowered the fees, significantly increasing the popularity and usage of the system. The Post Office noted the success and profitability, and it took over the system in 1838. Fees were further reduced and usage increased further, making the money order system reasonably profitable. The only draw-back was the need to send an advance to the paying post office before payment could be tendered to the recipient of the order. This drawback was likely the primary incentive for establishment of the Postal Order System on 1 January 1881.