Virtual humans are human-like characters that may be seen on a computer screen, heard through a speaker or accessed in some other way. However, a precise definition of what represents a virtual human, or even ‘artificial intelligence’ (AI), is challenging. Like-wise, establishing the distinctions between different types of virtual human, such as a chatbot, conversational agent, autonomous agent or pedagogic agent is unclear, as is how virtual humans relate to robots and androids. This chapter presents an introductory analysis of component parts of a virtual human, examines the traits that are important when considering virtual humans. It examines existing definitions of a virtual human before developing a practical working definition, and argues for a spectrum of virtual human types, and presents some common examples of virtual humans.