This guide discusses Case studies, how they can be used in your work, and how to source them:
According to the Cambridge Dictionary, a case study is:
a detailed account giving information about the development of a person, group, or thing, especially in order to show general principles:
(Source)
A case study is a detailed, in-depth examination of a single subject — such as a person, group, event, organization, or situation — to understand it within its real-life context. They may be real and based on actual events, or sometimes a story exemplifying a situation. In both cases, they show a realistic situation, which can have theory applied to.
The goal of the case study is to gain insight a situation and learn from it.