hdr is an acronym of the words high dynamic range. in photography, it is a post-processing technique in which multiple exposures of the same image are merged into a single image that contains detail and information from all of the images.

for example...

the images created by this process are surreal, captivating, haunting, and frequently gorgeous. some more information and examples.

• ten images from tokyo that look like something from batman


• the flickr hdr group


• the flickr best of hdr group


• pictures on flickr tagged 'hdr' sorted by interestingness


• a cool hdr self portrait


• a breathtaking look at a subway tunnel


• this cemetary entrance looks like something from half life 2


• a set of pictures of manhattan featuring some great hdr cityscape shots


• for some odd readon this photo screams 'alt.country cd cover' to me


• hdr article at wikipedia