Permission to Use Content
Some users have misconceptions about copyright and permission to use other peoples' content. This page is here to help correct a few of these misconceptions.
No copyright notice
A lack of a copyright notice does NOT imply a lack of copyright. The notice is not required.Quote from Wikipedia:
“In the United States, copyright has been made automatic (in the style of the Berne Convention) since March 1, 1989, which has had the effect of making it appear to be more like a property right. Thus, as with some forms of personal property, a copyright need not be granted or obtained through official registration with any government office.”
Just because you found an image on a website and even if tons of sites are using the picture, that doesn't give you the right to use it. The author of the content has to grant permission (and do so explicitly in writing). If you found an image on a website and it doesn't have a statement saying that you are allowed to use the image, then you cannot use the image. In many cases, you may contact the author (presuming they are the original author and/or copyright holder) and obtain their permission directly. Either way, you will need to provide either a link to their permission statement on their site, a copy of an e-mail from the author granting use, or other similar explicit permission statement.
If you've modified someone else's image and created your own derivative (e.g. taking the BZFlag tank icon and slapping a decal logo on the side), the original author must have explicitly granted permission to create and redistribute that derivative. You may find it hilarious to draw a moustache on a likeness of Steve Jobs that you want to use on your server, but unless you have a statement from the person that took the original picture that grants you that right, then the image cannot be hosted. Sites that say their content is available under many of the licenses that we've already listed allow derivative works (e.g. LGPL, BSD, CC-by, etc).
Open Source terms
Only images that are available under OSI-approved terms or under one of the allowed Creative Commons license will generally be approved for hosting. If you are the original author, using either the LGPL, BSD, CC-by, CC-by-sa, or public domain terms for your content is highly recommended. Content that does not fit the terms of the Open Source definition is not allowed with this service even if you are the copyright holder.