The document provides information on several early 20th century photographers and their contributions to the development of photography as an art form, including Alfred Stieglitz, Edward Steichen, Gertrude Kasebier, Clarence White, and others. It discusses the founding of the Photo-Secession and 291 galleries by Stieglitz and Steichen to promote photography. It also provides biographical details and examples of works by these pioneering photographers.