Gestures have long been considered an interaction technique that can potentially deliver more natural, creative and intuitive methods for communicating with our computers. For over 40 years, gestures provided an alternative to the keyboard and mouse for most application domains, employing an array of technologies to control a multitude of tasks. But how do we make sense of the expanse of this technique so that we may approach gestures from a theoretical perspective and understand their role in human computer interactions? Existing research tends to focus on the technology, exploring novel methods for enabling gestures and the tasks they can afford. However, few researchers have approached the discipline with the intent of building a cohesive understanding of gestures and the relationships that exist between the different systems and interaction styles. This work presents a theoretical framework to support a systematic approach to researching and designing gesture-based computer interactions.