Per the USPTO, a trademark "can be any word, phrase, symbol, design, or a combination of these things that identifies your goods or services. It’s how customers recognize you in the marketplace and distinguish you from your competitors. ...
A trademark:
Trademarks can be many different things including words, designs, logos, slogans, symbols, colors, sounds, even fragrances! Basically anything you can argue helps a consumer distinguish the source of a good or service.