Trademark vs. copyright
A trademark is a phrase or symbol that functions as an indicator of a brand. The concept stretches back to ancient times, when skilled artisans working with metal or ceramic would imprint their own distinct mark, called a maker’s mark, on the finished product. Today, you can often distinguish between a high-quality piece of jewelry and a knockoff by the maker’s mark. A registered trademark is a legal enforcement of such a mark, both for physical products and for digital assets.
Virtually anything can be a trademark. Words, images and specific decorations can all count. A trademark has an associated “strength,” which is how defensible it is as your unique mark versus how widely it can be used by other entities.
For example, the Apple logo with the bite taken out of it is a fairly strong trademark. Other entities are generally unable to use that specific symbol defensibly. On the other hand, Apple trying to trademark the word “apple” would be very weak; a bakery using apples is not in violation of Apple’s registered trademark if it describe its pies as apple pies. Big Apple Bagels isn’t in violation for using its city’s nickname.
A very strong trademark is one that is completely made up. The brand name Xerox is one example. There was no entity or name called Xerox prior to the company creating the name and using it in its branding. It’s very strong now, as any other use of it is necessarily in reference to the company.
Generally, trademarks should be registered. While you don’t need to register a trademark, a registered trademark allows you to make your mark public knowledge and gives you precedence against future similar marks being registered.