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.
Candid photos are usually simple photos without a lot of technical equipment or any time taken setting up the shot. Thus they capture some wonderful slices of life!
It's rare to get a second chance with candid photography.