Grounded in the US Constitution, US Copyright laws protects a creation that is fixed in a tangible medium. At the moment the creation is fixed, a copyright is automatically secured.
That is, if someone stands up on the street and recites a poem that s/he just created, those words are not protected until the words are written on paper, or written on a computer or a video recording is made of the words being spoken. But once that happens, the creator has automatically secured a copyright. However, a creator cannot protect the “idea” represented by the creation, only the actual physical representation. In other words, if one writes a story, the actual written words are protected from being copied, not the ideas represented by those words.
For example, if a writer describes a futuristic device that allows a person to speak a foreign language when implanted in one’s head without previous knowledge of that language, the writer cannot prevent someone from creating such a device by claiming a copyright on that idea. Only a patent can protect an idea.
Additionally, there are other categories of materials that cannot be protected by copyright: 1) titles, names, short phrases and slogans, 2) familiar symbols and designs, 3) ingredients for a recipe, and 4) works that have no original created material.
There are various reasons to obtain a registered copyright: 1) One cannot assert one’s copyright right in a court unless a registered copyright has been obtained, 2) registered works are eligible for statutory damages, as well as attorney fees and 3) if registration occurs within 5 years of publication, one does not need to prove the validity of one’s copyright by substantial evidence.
Interestingly, two separate people can have a copyright on very similar stories if it can be shown that both created the stories without knowledge of the other’s work.
The copyright laws protect a work created by a single creator from the moment the work is secured in a tangible medium for the creator’s lifetime plus seventy years.