Triangulation is classically defined as looking at one research object from different perspectives. However, this large and consensual definition masks different approaches to triangulation and ignores its historical evolution since its emergence in social sciences literature. In order to gain a better insight into its current definitions, we will first propose a brief historical overview and highlight its different meanings. Then, we will illustrate how triangulation can be used in a research design in order to gain extra-knowledge. Finally, we will talk about MIXED METHODS RESEARCH and its relationship with triangulation.