Candid portraits involve capturing the photo when the subject thinks the photographer isn’t working. However it will still be staged and they would still have direction from the photographer. What they do not know is exactly when the photograph will be taken.
Examples of Candid photography:
Street photography, a genre of photography that records everyday life in public places. Being in the public setting enables the photographer to take candid pictures of strangers, sometimes without them knowing. Street photography does not have to be taken on the streets. You can do street photography anywhere. The aim of street photography is to capture culture and lifestyle.
A good street photo needs a clearly defined subject and use composition techniques such as rule of thirds, negative space, symmetry etc. Images should tell a story or document a moment. Some street photography is created to make the viewer pause and question themselves.
https://photographylife.com/what-is-street-photography
Examples of Street photography:
http://www.artnet.com/artists/lee-friedlander/
Good blog post, informative and interactive too.
Aim to add your recent portrait experiments in the studio as soon as possible!