What are the main purposes of a trademark?

The main purpose of a trademark is to prevent the public from being confused about the true source of goods. By doing this, a trademark also helps to assure that the trademark owner, and not an imitative competitor, will reap the many rewards associated with a desirable product. Trademarks also let the public know that the quality of the goods (e.g., a DELL® laptop) is the same no matter where you buy it.