A Trademark is a distinctive word, name, symbol or device that indicates the source of goods. Similarly a Service Mark is used to indicate the source of a service. In other words, trademarks allow businesses to distinguish its goods and servces from competitors. Trademark protection may be available for your company's brandname, catch phrase, logo, symbol, design, image or website domain name.
By merely adding a "TM" or a "SM" in your everyday use, you may already be asserting your common law Trademark rights. Common law rights are typically limited to geographical use. So if you mark your product with a "TM" and only sell in San Diego, the mark might not be protectable in Phoenix. However, a "TM" or "SM" may assist you in preventing others from using your Mark within your region of use.
A Federally Registered Trademark is signified by a "®" and provides protection nationwide. To qualify for a registered trademark the mark has to be used in interstate commerce. A Federally Registered Trademark results in a greater variety of remedies for enforcement than a common law trademark. Some advantages to a Federally Registered Trademark are that a Registered Trademark: