Free imagery

Due to the widespread use of digital cameras there are almost as many photos under Creative Commons license as there are freely accessible MP3s: the lower the threshold for creating something the higher the number of people who make their creations accessible to all. One possible stop is, of course, Flickr, where a whole section is reserved exclusively for CC-licensed images. Advantage: the Flickr section is subdivided into the various CC types - one can tell at a glance whether an image may be used commercially or in derivative versions created using Gimp or Photoshop. With a library of almost 35 million images it is likely that any conceivable target audience will find what it is looking for.

Flickr
Only a small selection of the millions of free images at Flickr

If even that seems too much hassle you can search flickrCC, a search front end for CC-licensed images at Flickr. Several alternatives to Flickr also explicitly offer images under free licenses - interesting, for example, for photo fans who don't wish to set up a Yahoo account. Still, the terms of use should always be thoroughly investigated: despite a long tradition of erotic and pornographic content in photography, many sites prohibit "adult content" – Mapplethorpe would have no chance on half of today's photo sites.

Open photo Some sites, by the way, only serve as meta search engines for free images and do not offer an upload facility. OpenPhoto is a web collection for searching and uploading, and so is Free Photobank. Free Photobank, however, forces photographers who upload images to agree to a "commercial use" CC variety which doesn't restrict image modification in any way. Clearly defined licenses are, of course, helpful for the users of image collections - however, those who wish to restrict or allow different things for individual images will prefer to use a site like Flickr.