A Creditor can raise a Bankruptcy Petition in relation to an individual where the Creditor (the person who is owed money) is able to show that the Debtor (the person who owes money) is unable to pay their debts as and when they fall due.
This only applies to individuals. There is a separate process called Winding Up, in relation to Companies that owe money.
There are various routes by which a Bankruptcy Petition can be raise. The most common is where a Statutory Demand has been served and not complied with.
The Creditor will file the Petition with the Court and will be given a return date, and a venue, for a Court hearing. At this hearing, the Court will decide whether or not to make a Bankruptcy Order against the Debtor.
This is a serious sanction for the Debtor. As such, it is a requirement that the Bankruptcy Petition is personally served upon the Debtor. If this is not possible, the Creditor must apply to the Court for an Order for service upon the Debtor by another method.