An Illinois Affidavit of Use is a sworn statement from a business entity or individual asserting that a trademark or service mark is being used in commerce in the state of Illinois. This document serves as proof that the trademark is being used to identify goods or services in the marketplace. It is often required to register or maintain a trademark in Illinois. There are two types of Illinois Affidavit of Use: use in commerce and use in connection with services. Use in commerce refers to the use of a trademark to identify and distinguish goods in the marketplace. Use in connection with services refers to the use of a trademark to identify and distinguish services in the marketplace.