A trademark is a sign that indicates an individual, business, or other legal entity. It is used to denote products or services that belong to that corporation or person. A trademark is M&M or Nike. A trademark does not have to be registered to protect the company or person. A trademark that is unregistered to promote or brand goods often has TM behind it. An unregistered trademark for services has SM. Lastly a registered trademark will have the R in a circle.
This will tell the consumer whether the product is protected by the symbol. It also helps a consumer recognize top brand names. There are issues with infringement occasionally with a product in which the company may have to seek legal proceedings to protect their product.