KPIs are quantifiable metrics that measure the success of organizations, projects, and activities. Effective KPIs are relevant, measurable, actionable, timely, and benchmarked. For release management, KPIs help align activities with goals, identify risks, enable continuous improvement, measure performance, optimize resources, support communication and decision-making, ensure quality, and promote accountability, ultimately leading to improved customer satisfaction. Example KPIs include release cycle time, defect density, release success rate, change failure rate, and metrics tailored for major and minor releases.