The term documentary photography came into use during the depression years, when telling pictures of poverty-stricken farmers awakened Americans to the need for social reform. And in many minds this field of photography still suggests picture of the Dust Bowl, of rural hardship and urban slums.

Yet as this book shows, there is, and always has been, far more to documentary photography than the recording of the world's ills. For there is much more to document than suffering and poverty: faraway places and exotic peoples, quirks of nature and society, the whole gamut of emotions and relationships. The subject matter is, indeed, almost unlimited.

Then is every photograph a documentary? Not really, for it must convey a message that sets it apart from a landscape, a portrait, a street scene. It may record an event, but the event must have some general significance, more than the specific significance of a news photo. It may record character or emotion -- but again, of some general social significance; it is more than personally revelatory, as a portrait is.

Yet whether it shows us family life in Paris or in Maine, the central square of Peking or a stretch of U.S. Route 66, a dive in New York's slums or a village café in Hungary, a sharecropper's cabin or a suburban living room, the documentary photograph tells us something important about our world -- and in the best examples, makes us think about the world in a whole new way.