Why is it called stamp duty?

Stamp duty is a tax that is levied on the legal recognition of certain documents, such as property transactions, share transfers, and insurance policies. The term "stamp duty" originates from the practice of physically stamping a document to indicate that the tax has been paid. In the past, a physical stamp was affixed to the document to show that the duty had been paid, and failure to do so would render the document legally invalid. While the physical stamping of documents may no longer be common, the term "stamp duty" has persisted as the official name for this type of tax in finance. It is essentially a tax on legal documents, and the term "stamp duty" reflects its historical origins and the way it was administered in the past.