A statutory demand is a form which includes details of the debt you owe. See an example of a blank statutory demand here.
The forms will normally be delivered to, or ‘served’ on you in person. This means your creditor or an agent working on their behalf will visit you to hand you the form.
They can send the statutory demand by post, but only if they’ve tried to serve it in person and been unsuccessful.
For debts which are regulated by the Consumer Credit Act, the creditor must have defaulted the account before they can issue a statutory demand.