Non-use cancellation is a legal procedure in trademark law that allows a party to petition for the cancellation of a registered trademark when the mark has not been used in commerce for a specified period, usually three consecutive years. This process ensures that trademarks reflect current market practices and prevents the cluttering of the trademark register with inactive marks. It is essential for maintaining the integrity of trademark systems, as it enables interested parties to challenge marks that may hinder competition due to their non-use.