Goals of Copyright: The stated goal of US copyright law is to promote progress by securing time-limited exclusive rights for creators. (paraphrased from Article 1, Section 8, Clause 8 of the US Constitution)
Exclusive Rights of Creators: Right now, in the USA, Copyright is automatic for content in a fixed form. If you write a book or draw a picture, those things are under copyright, and you are entitled to six exclusive rights about them:
- The right to reproduce
- The right to create derivative works (eg: adapting a book into a play)
- The right to distribute copies, or transfer ownership of the work
- The right to perform the work publicly
- The right to display the work publicly
- The right to perform the work publicly via digital audio transmission (if sound recording)
You are not required to register your copyright with the Copyright Office. You are not required to include a copyright statement. If you anticipate that your work will be a high-value project, or that there may be a copyright dispute in the future, you can register with the Copyright Office.
There are limitations on these exclusive rights, the most common of which are Fair Use and Reproduction by Libraries and Archives (for an exhaustive list, see: US Code, Title 17, Chapter 1, Section 107-112.
Things that cannot be copyrighted: Facts cannot be copyrighted, which means that things like basic math, recipes, alphabets, grammatical tropes (eg: “I before e, except after c”) and recipes (the list of ingredients and steps themselves) cannot be copyrighted.
On the other side, ideas cannot be copyrighted either. Only creative media in a fixed form is eligible for copyright.