The Internet has provided countless new ways for ingenious businesses and individuals to refer to a plaintiff’s mark in a manner that inpacts the plaintiff’s business. These new methods may not directly associate the mark with goods or services that the defendant is offering for sale and may be completely hidden from consumers’ view. In evaluating the numerous trademark infringement and dilution suits that these unauthorized references have generated, courts have often failed to focus on the appropriate role of the “trademark use” requirement, which has traditionally limited the scope of the trademark infringement (and more recently, trademark dilution) cause of action. Some courts appear to have completely ignored the trademark use limitation, while others have acknowledged the limitation but construed it in a manner that undercuts or distorts it. This has given rise to a number of splits in the Circuit Courts of Appeals. This Article undertakes to bring some focus and coherence to the trademark use issue in the Internet context. It provides an in-depth examination of the history and purpose of the limitation and proposes a modern, general definition of “trademark use” in light of that history and purpose. It then demonstrates how this definition should apply in several important contexts on the Internet.