This document provides background information on expertise and expert performance. It begins by explaining why expertise is important to learn in higher education and outlines different levels of expertise, distinguishing between routine experts and adaptive experts. It then discusses definitions of expertise over time. The document covers domain-specific expertise in various fields and describes the progression from novice to expert in five levels. It also addresses stereotypes related to expertise and how experts can excel as well as occasionally fall short. Finally, the document discusses expertise in the context of work life, how experts define expertise, and expertise as an increasingly social and collaborative phenomenon.