In addition to storing a plethora of code and functionality, devices also possess a certain set of data and commands, known as firmware. The ability of devices to perform specific tasks relies on the firmware. In order to understand the scope of firmware we conducted a qualitative analysis of its properties, functionalities and security. We examined the use of the terminology over a period of years and found that “firmware” is used in numerous situations in a range of contexts. In this paper, we propose a taxonomy of firmware to classify the field and understand it better.