Photos that form a story come under this style.
It is about a particular subject or story that a photographer wants to explore.
They are all objective pictures and are often about a war, cultural issues or chronicling significant events, such as a celebrity or Bride/groom
It often comes from spending some time with the person, talking and listening to their story so far and then capture what comes naturally similar to Candid photography. The pictures then tell a full story.
You can check out how I use a documentary style for a wedding shoot here