Copyright law reserves rights for creators (and often their employers) to reproduce, share, adapt, and perform what they create.
Copyright applies to tangible materials that have even the tiniest bit of creativity. Art works, written documents, and sound recordings are protected because they are original and can be physically copied or shared. Facts are not protected because they are not original; ideas are not protected because they are not tangible.
Copyright is automatic; if your creation is eligible for protection, there's nothing else you're required to do. That article you wrote? That stick figure you doodled in class? Both are automatically protected. However, you can register works with the U.S. Copyright Office, and that's a good idea if you want others to find a record of your copyright.
The Copyright Act grants creators protection in their works by bestowing upon them a bundle of exclusive rights with respect to their works:
Copyright protection is automatic and begins the moment any “original work of authorship is fixed in a tangible medium of expression.” Copyright protection does not require any form of copyright notice or registration with the U.S. Copyright Office, although affixing a notice and registering a work enhances protection of the owner’s rights.
Copyright protection does not last forever. For new works created in the United States, protection begins with creation of the work and lasts 70 years after the date of creation. At that time, the work passes into the public domain, meaning it may be legally shared, copied, and adapted without permission. For older works created in the United States, cessation of copyright protection and passage into the public domain depends on a variety of factors. See the Cornell Public Domain Chart or the Public Domain tab of this guide for more information.