Service Mark

Most people never notice this one, and the difference between it and the trademark symbol is a point of law. Where the trademark sign claims rights in a brand attached to goods, this small superscript SM claims the same for a service — a consultancy, an airline, a cleaning company, anything you sell as work rather than as a product. Both are the informal, do-it-yourself notices: you can attach either without registering anything, simply to assert that you regard the name as yours.

The symbol that requires paperwork is the registered sign, which in the United States you may legally use only once a mark is actually registered with the trademark office; putting it on an unregistered name is a misstep, so this mark and the plain trademark sign are what you reach for in the meantime. The distinction between goods and services is largely American practice and often ignored in casual use, but it is real, and using it correctly quietly signals that what you are protecting is a service. As a superscript character it is designed to sit small and high against the word it follows, not on the baseline.