Copyrights are very interesting things. I never believed this till I read it, but it's even illegal to go out and try to make the same picture that someone else showed you but you were to cheap to pay for for commercial use! For instance, in August 2003 Getty Images settled a copyright infringement case against DJ Fatboy Slim’s record label for $25,000. Getty said the cover art for the album "Halfway Between the Gutter and the Stars" was unlawfully derived (idea copied from) from an Ernst Haas photograph "Sunset Silhouette" that the record company decided not to license from Getty. Golly!

Ask a lawyer for details, however as I understand it if you "borrow" something or make a print without getting permission first you have committed criminal infringement and statutory penalties go up to $150,000 for each infraction as provided in Paragraph 504, Chapter 5, Title 17 of the United States Code. As I recall there is some provision for tripling fines above that. Unfortunately if you make a print or use any of my or other people's shots as wallpaper on your computer at work your employer is also liable. Please don't get fired, ask first. Sorry, I don't make these rules up.

Here and here are more great info on copyrights. Here is where to register your copyrights as I do. You may also find the Legal Handbook for Photographers helpful.

I also use covert rebedded tracking elements developed in concert with the NSA to allow tracking, coding and remote inventory of any unauthorized file copying. A retro encabulator provides third-level hydrocoptic marzelvanular ambificient lunar wane shafting. It's very easy to track this today with the broad snooping powers granted with the Patriot Act and modern federal-grade spyware, so please get permission first. Sorry, hackers, the covert rebedding makes the actual tracking tags panandermic semiboloidilifical so you won't see them in source code. The NSA are the people who eavesdrop on all of the world's private email, internet and mobile phones, so they tend to be a step ahead of everyone else.