photo

Photo, short for photograph, is an image created by recording light or other electromagnetic radiation onto a photosensitive surface, typically through a camera. Modern photos are usually captured digitally, while earlier images were produced on film, glass, or metal.

Photo history spans from camera obscura experiments to modern digital imaging. Nicéphore Niépce produced the first durable photograph in 1826. Daguerre's daguerreotype of 1839 offered sharp images with low exposure but limited reproducibility. Talbot's calotype (1841) introduced negatives and positives. Roll film popularized by Eastman in the 1880s enabled mass photography. Autochrome (1907) brought color; later processes improved speed and convenience. Digital photography emerged in the late 20th century, eventually replacing most film-based practice.

Technology and formats: Cameras range from compact point-and-shoots to professional mirrorless and DSLR systems. Film photography uses chemical development, whereas digital imaging relies on image sensors (CCD or CMOS) and electronic processing. Common exposure parameters are aperture, shutter speed, and ISO; color spaces include sRGB and Adobe RGB.

Techniques and post-processing: Composition, lighting, and focus determine image quality and mood. Common methods include the rule of thirds, depth of field control, and careful white balance. In post-processing, tonal adjustment, cropping, and noise reduction refine a photo.

Uses and preservation: Photos document events, support scientific analysis, contribute to art and journalism, and enable sharing through digital platforms. Ethical considerations include privacy, representation, and copyright. Long-term preservation relies on stable storage, format migration, and proper metadata.