The document discusses employee retention, including its definition, importance, and evolution over time. It begins by defining employee retention as an organization's ability to retain employees and the strategies used to do so. It then discusses the importance of retention for reducing costs and maintaining organizational knowledge. The document traces the evolution of retention from a focus on employee satisfaction in the 1970s-80s to a greater focus on engagement and linking it to business outcomes starting in the 1990s. It also discusses drivers of engagement like trust and the future of sustaining engagement.