Copyright protects original works of expression, such as novels, fine and graphic arts, music, audio recordings, photography, software, video, cinema, and choreography by preventing people from copying or commercially exploiting them without the copyright owner's permission.
Copyright laws do not protect names, titles or short phrases. That's where trademark law comes in. Trademark protects distinctive words, phrases, logos, symbols, slogans, and any other devices used to identify and distinguish products or services in the marketplace.
There are, however, areas where both trademark and copyright law may be used to protect different aspects of the same product. For example, copyright laws may protect the artistic aspects of a graphic or logo used by a business to identify its goods or services, while trademark may protect the graphic or logo from use by others in a confusing manner in the marketplace. Similarly, trademark laws are often used in conjunction with copyright laws to protect advertising copy. The trademark laws protect the product or service name and any slogans used in the advertising, while the copyright laws protect the additional creative written expression contained in the ad.
For more information about copyright law, see the Copyright section of Nolo's website.
Whether you're investigating patent, copyright or trademark law, get Patent, Copyright & Trademark: An Intellectual Property Desk Reference, by Richard Stim (Nolo), the most concise and comprehensive explanations of intellectual property in one volume.