That new book you bought, there is a trademark for the publisher. Stop by and pick up a CD there is a trademark on it. When the title sequence of a movie goes by? There are several trademarks, at least one for each company. As a general statement, most consumer products have a trademark attached to them.
Trademarks help identify and associate products with the company creating the product. Because of this, the authority for a trademark is in statute. This is different from copyrights and patents, which are derived from the Federal Constitution. In a practical sense, the effect of this difference is only noticeable by an attorney who has spent time looking into the issue.
The reason you should file your trademark with the USPTO (United States Patent and Trademark Office) is to protect your brand. By registering you gain several benefits otherwise not available, including a presumption in favor of your trademark. In the event you run into a company with a confusingly similar icon or other trademark, you can get them to stop using it. However, a word of warning. Failure to register your trademark can mean another party can trademark it first. In that instance, you would be unable and legally barred from using the mark.
If you are looking into starting a business, trademark protection may be a vital element. If you are going to have consumers of any kind, your trademark will be what tells your consumers your product is yours. This can be an issue that can be lost in the shuffle of the excitement and focus on the core business documents. Remember that when setting up the business ensuring your trademark may be just as important as any other legal document.