This document provides an overview of how social media is used in human resource management. It begins with definitions of key concepts like social media and social networking sites. It then discusses how social media can be used internally in HR for communication, training, employee management, and building relationships. Externally, social media is used for recruitment, compensation/benefits, building relationships, maintaining corporate brand, and promotion. Both strengths and weaknesses are identified, such as social media being cost-effective but also requiring time to learn tools. Case studies of companies' social media use in HR are also reviewed.