When you run a business, you want to make it stand out. Most businesses do this by creating a service mark or trademark. Each has its own purpose.
These symbols represent products and are an asset of the company. It's important that they're protected and aren't infringed upon. Infringing on a trademark could confuse customers and make them think they're buying something they aren't.
What is a trademark?
Trademarks are specially designed logos that identify a product. A good example is a brand name, like Apple, which has an apple-shaped logo. Trademarks aren't the same as service marks. The trademark's job is only to identify goods from one company over the goods of another.
What is a service mark?
Service marks identify a service (as opposed to a trademark, which identifies a product). To take the example of a slogan used in a photography business, a service mark might be "Quick snaps!" to indicate that you take photos quickly or in reasonable time frames.
(Note that service marks, however, are not limited to slogans, and slogans themselves can also apply to products and trademarks.)
Both trademarks and service marks are kinds of intellectual property. Following the trademark or service mark, you may notice the "R" symbol. This is a symbol that shows that the mark has been registered officially with the U.S. Patent and Trademark Office.
Trademarks and service marks are both types of intangible assets. They have no material substance, but they are valuable to the company. If yours has been used by someone else, it's well within your rights to want to put an end to it, and there are legal actions you can take.
Source: The Balance, "Trademarks and Service Marks - What's the Difference?," Jean Murray, accessed Oct. 05, 2017