This document discusses virtual reality (VR) and its applications. It covers topics like VR presence and telepresence, using VR for training purposes like aircraft training, and how VR allows researchers to conduct experiments that can't be done in real life. It also discusses defining elements of VR like tracking, rendering and reacting to user behavior. Additionally, it examines the Proteus Effect where characteristics of a user's avatar can influence their own behaviors and factors that influence the feeling of presence in VR.