What is the difference between a trademark and a service mark?

Trademarks are words, phrases, symbols, designs, or any combination thereof that helps identify the source of a specific product or good. Service marks are similar to trademarks, but identify the source of a specific service. Services, by definition, are performed activities, either for pay or otherwise, and can be performed by either a business or a person for the benefit of others. Often the term “trademark” is also used to describe a service mark.