From Social Patterns
Copyright is a form of intellectual property that gives the creator of an original work exclusive rights for a certain time period after which time the work is said to enter the public domain. These rights include publication, distribution and adaptation. Copyright covers published and unpublished literary, scientific and artistic works, whatever the form of expression, provided such works are fixed in a tangible or material form.
"Copyright" literally means the right to copy.
Internationally, copyright has been somewhat standardized, lasting between fifty to a hundred years from the author's death, or a finite period for anonymous or corporate authorship, but there are no "international copyrights" that enable you protect your work throughout the world.
Most countries are signatories of the Berne Convention and the Universal Copyright Convention (UCC), which allow you to protect your works in countries of which you are not a citizen or national. The 1886 Berne Convention first established recognition of copyrights among sovereign nations, rather than merely bilaterally. Under the Berne Convention, copyrights for creative works do not have to be asserted or declared, as they are automatically in force at creation.
"Fair use" is a doctrine in United States copyright law that allows limited use of copyrighted material without requiring permission from the rights holders, such as use for scholarship or review.