A trademark is a word, phrase, symbol, or design — or a combination of those things — that identifies and distinguishes a provider of goods or services. In your case, the service you provide can be considered to be a continuous series of cartoons, such as a daily comic strip. Therefore, any images that identify your work — a logo, for example — need to protected with a registered trademark.

The U.S. Patent and Trademark Office Web site ( www.uspto.gov) has detailed information on the topic. They also have a search engine you can use to find out if another individual already owns the trademark on the combination of words, phrases, symbols, or designs that you're trying to register. Filing a trademark is expensive — you'll pay over $300. Many cartoonists find adequate protection in a copyright, but if you have a recognizable logo or slogan, you may wish to consider registering a trademark.