Congress passed the United States' first federal copyright law in May of 1790, and the first creative work was registered less than two weeks later. Copyright laws protect the rights of authors who create original creative works to control how that work is distributed, copied, performed or displayed for a limited time. Photographers who copyright their work control how that image is used for the rest of their lives plus 70 years.
Copyright laws state the owner of a copyright is the "author" who created the work. With photography, the author is the individual who took the picture unless that individual was working for a studio or business when taking the photo. If a photographer captures an image as an employee, the author of that work becomes the company for which the photographer works. Individuals who have their photo taken by a photographer cannot claim ownership of that photograph.
Previously, a photo became copyrighted immediately after being developed, but in today's age of digital cameras a photographer's work becomes copyrighted the moment they take the picture. The photographer then controls the right to copy the image, and how the original photo may be displayed. The photographer also controls any image based on her original work. Copyright laws allow photographers to sue for damages if their photos are displayed or copied without their permission. If a copyrighted photo is used commercially without permission, the photographer is entitled to receive all proceeds gained from the use of her work.
Developed through the years over the course of multiple court cases, the doctrine of "fair use" has become apart of copyright law. Fair use allows those who are not the copyright holder of a work to use that work under certain circumstances. The displayer can only show the work and avoid copyright infringement if the use is for non-profit educational purposes, and displaying the work does not harm the commercial value of the piece.
To use a copyrighted photo, a licensed agreement must be worked out between the copyright holder and the photo's user. Purchasing a copy of the photo, or paying the copyright holder an agreed upon sum of money to display the image are two possible types of licensing agreements. A photo is part of the public domain when the copyright on that photo has expired and not been renewed. Works in the public domain can be used without a licensed agreement.