Travel photography is a subcategory of photography involving the documentation of an area's landscape, people, cultures, customs and history. The Photographic Society of America defines a travel photo as an image that expresses the feeling of a time and place, portrays a land, its people, or a culture in its natural state, and has no geographical limitations. Many others are doubling up as educators in the field of ambient light photography. Some of them are doing assignments which intrinsically use their strengths, e.g. shooting exteriors or interiors of buildings for architects and interior designers. The mission of this association is to promote and enhance the art and science of photography in all its phases, among members and non-members alike. The PSA holds several notable competitions throughout the year, including the PSA Youth Showcase. The magazine eventually prevailed in the dispute, and in July 2009 it resumed publishing a compilation containing all issues through December 2008. The compilation was later updated to make more recent issues available, and the archive and digital edition of the magazine are available online to the magazine's subscribers. Photography has many uses for business, science, manufacturing (e.g. photolithography), art, recreational purposes, and mass communication. The discovery of the camera obscura that provides an image of a scene dates back to ancient China. Leonardo da Vinci mentions natural cameras obscura that are formed by dark caves on the edge of a sunlit valley.
