Candid photography is by meaning taking pictures of people when they are unknowing. Part of the fun in photography is catching your human subject's off guard so that your pictures have more emotion. Photographers who work for magazines, like Time Life, have managed to get candid shots of their subjects. I think most of us can remember the black and white photographs of Africans and others giving rise to more emotion from the viewer. Taking candid shots may occur easy although there are few techniques in the photography world that will make the candid shot worth much more than just a snap shot of close friends.
First and certainly most essential is to keep the subject in view while they are not paying attention. The next step is training your eye to catch the moment. You have to be able to move fast, but with design. You need to have your camera set for the picture before you are even aware you will take the photograph. The best way to do this if you have a digital or automatic camera is to keep it on the proper setting. Manual cameras take moments to focus and can loose the candid shot if your subject becomes aware of you. See portrait photography specials
Candid photography relies on the light; however, you may not always get to choose the angle. The angle could be where you are standing at the time. As a photographer of candid photography, you know the importance of choosing the best angle at the right moment that is possible.
The entire point of candid photography is to gain the unguarded moments of a person's emotions, whether it is tears, happiness, love, or other emotions. While it is true, you need to have light, angle, and a good camera to catch the shot it is more important to observe. Most photographers are trained observers. Their eyes will wander over the crowds, landscape, or other setting searching for the perfect shot. They will always have a camera ready. It can be extremely hard when you are taking photographs of your friends because they tend to be more involved in the conversations or activity.