Copyright

Copyrighted Photos --- the exclusive right to make copies, license, and otherwise exploit a literary, musical, or artistic work, whether printed, audio, video, etc.: works granted such right by law on or after January 1, 1978, are protected for the lifetime of the author or creator and for a period of 50 years after his or her death.
http://gimp-savvy.com/PHOTO-ARCHIVE/UFWS/page1.html


Stock Photos --- are photos which are available for rental or purchase for commercial use. They can be obtained from an image bank (a company which makes its business renting use of stock photos) or on disks which can be purchased. Most image banks show their material on the Web. Different price scales apply to images according to their source, their quality, their resolution, and how specialized their subject matter is.
http://www.istockphoto.com/index.php


Public Domain Photos --- The status of photos, publications, products, and processes that are not protected under patent or copyright.
http://pdphoto.org/PictureHome.php?cid=17&mat=pdef&md=cid


Royalty Free Photos --- Clip art, images, graphics, photographs, art, music and other created content which may be offered to the public or individuals (normally for a specified amount of money) to be used in specified ways (terms of usage). The creator retains all copyrights and publishing rights. You may use and publish the clip art, images, music per the specified terms of usage but may not sale or distributed to a 3rd party.
http://www.jupiterimages.com/


Model Release For Photos --- A model release, known in similar contexts as a liability waiver, is a legal document typically signed by the subject of a photograph granting permission to publish the photograph in one form or another. The legal rights of the signatories in reference to the material is thereafter subject to the allowances and restrictions stated in the release, and also possibly in exchange for compensation paid to the photographed.
http://www.danheller.com/model-release-primer.html