In this chapter, we discuss the idea of ‘paradigms’ of concurrency and the pivotal role of histories as abstract representations of behaviours of concurrent systems. A history groups together observations of concurrent behaviour which only differ in inessential details, and can therefore be regarded as being underpinned by the same concurrent run. The role of a paradigm is to capture key structural properties of histories resulting from some fundamental features of a concurrent system from which they have been generated, e.g., that independent actions executed in two separate parts of the system can be executed in any order.