A patent gives its owner the legal exclusive right to his or her invention for a limited period of time. After the term of a patent expires, the technology become public domain to benefit of society. A patent is granted by a country's intellectual property office which in the United States is the United States Patent and Trademark Office (USPTO).
A copyright protects the intellectual content of artistic, literary and musical works such as a book, manuscript, musical score or photograph. See What Does Copyright Protect? Copyrights are registered with the United States Copyright Office.
For further explanation, watch the USPTO video Basic Facts: Trademarks, Patents and Copyrights.
According to United States Code, a trademark is "...any word, name, symbol or device used in trade to indicate the source or origin of goods or services, and to distinguish them from the goods and services of others." Examples of current or past trademarks include-
Unlike patents, U.S. registered trademarks are not limited in duration. They are valid as long as the trademark continues to be used in commerce and maintenance fees are paid regularly. Similar to patents, trademarks are also administered by the United States Patent and Trademark Office (USPTO). Information about United States trademarks is found on trademarks section of the USPTO website.
It's important to remember that not all applications are accepted by the USPTO as trademarks especially if they are merely descriptive of the product or if there is a likelihood of confusion by the general public with another existing unrelated trademark. Also, even if a trademark used in commerce is not registered with the USPTO it is considered common law usage which provides legal protection in the local geographic location where it is used.
Please see the USPTO's Trademark Basics Registration Toolkit to understand the trademark registration process.
The New York Public Library Thomas Yoseloff Business Center is a Patent and Trademark Resource Center (PTRC) with the USPTO.