Candid photography is best described as un-posed and unplanned, immediate and unobtrusive. This is in contrast to classic photography, which includes aspects such as carefully staged portrait photography, landscape photography or object photography. Candid photography catches moments of life from immersion in it.source
Candid photography is opposite to the stalking involved in animal photography, sports photography or photographic journalistic intrusion, which all have a focus on getting distant objects photographed, e.g. by using telephoto lenses. Candid photography's setup includes a photographer who is there with the "subjects" to be photographed, close, and not hidden. People photographed on candid shots either ignore or accept the close presence of the photographer's camera without posing.
The events documented are often private, they involve people in close relation to something they do, or they involve people's relation to each other. Candids are the kinds of pictures taken at children's birthday parties and on Christmas morning, opening the presents; the pictures a wedding photographer takes at the reception, of people dancing, eating, and socializing with other guests.