A copyright is a protection provided by the US Government to anyone creating a work. The work can take any form. Its primary characteristic is it “expresses an idea.” The copyright does not protect or restrict the underlying idea. It only protects the expression of that idea; typically in words, painting, sculpture, music, theater, etc.
A copyright lasts for the lifetime of the author plus 75 years. The rules are a bit more complicated for material created by a group. Talk to a lawyer about that situation.
A copyright is issued by the national government and is only good within that countries jurisdiction. However, there is an international copyright convention. Talk to a lawyer if you need more on that convention.
The basic US Copyright law has changed considerably in the last few years. Under the current law, a copyright can exist in several forms. The act of expressing an idea results in a common law copyright as soon as you complete the expression. No formal action is required. However, this common law copyright is of limited value. It is hard to defend in court. A second situation occurs when you “assert your copyright.” In this case, you provide notice of your copyright by adding the following statement to the document in a prominent location, “Copyright 2009, <owner’s name> or the briefer “© 2009, <owner’s name>.” The third situation is the strongest. You go to the website of the Library of Congress, www.loc.gov and click on the Copyright Office in the left column. The site contains some important tutorial material and a FAQ page. After reviewing their guidance, you fill out the specific form for your type of expression, text, movie, music etc., pay a nominal fee (about $35) and submit two copies of the work, or various parts thereof in the case of a computer program, to the Government address provided. You are then entitled to use the notice “Registered Copyright 2009 <owner’s name>.” This can be shortened to Reg Copyright 2009 <owner’s name> or ® 2009 <owner’s name.” If you ever need to go to court to protect your copyright, the Government will certify to the date they received your two copies of the work.