Our Founding Fathers considered copyright carefully and covered it in article 1, section 8 of the Constitution when they wrote, "The Congress shall have Power To ...promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries"
Not in their wildest imaginings, however, did they understand what technological changes would occur that would affect copyright questions in the 21st century. The ability to easily copy, download, digitize, email, and/or scan have all added wrinkles to how copyright is interpreted and enforced. Oddly enough, as information has become more available, the ability to re-use copyrighted materials - and understand what can and can't be re-used - has become more difficult. Many believe that the copyright law is out of date and in need of revision in order to be more in-step with the electronic age in which we live.
What is the purpose of copyright?
Copyright is the exclusive right of ownership given to someone who creates a work in tangible form. These exclusive rights are embodied in section 106 of the Copyright Act:
However, in order to have a strong and intellectual public, Congress limited these rights so that others could use the copyrighted material to make new works and use past works to lead to new and better ideas, discoveries, research, plays, etc. These exclusive rights can be exempted, if the circumstances warrant it. The law spells out what these exemptions are; for indidivuals, that would generally be the fair use exemptions. See tab "Public Domain and Fair Use."
It used to be that everything that was copyrighted displayed the copyright symbol - ©.
That all changed in 1988 with the Berne Convention Implementation Act, which made it optional to use the copyright symbol on works published after March 1, 1989. Since then, works no longer need to be registered (have the © symbol) to be copyrighted; they are covered by copyright the instant they are put into tangible form.
Note: A work must be registered if the copyright holder wants to claim an infringement of their exclusive rights.