This chapter outlines the definition of sarcopenia and the challenges faced by the scientific and clinical community in obtaining a universally accepted definition. Because sarcopenia is a risk factor for a multitude of adverse health outcomes, the chapter discusses the strengths and weaknesses of recent diagnostic criteria (sarcopenia algorithms) to identify older people with sarcopenia outlined by experts across the world. In particular, the assessment tools and their cut-off points (reference values) for muscle mass, strength, and physical performance are highlighted. Attention is also given to the available screening assessment tools, which provide opportunities to identify older people at risk for sarcopenia in large communities or settings. Identifying effective interventions to combat sarcopenia is paramount; thus, the chapter highlights the available published evidence where the participants of the study were identified as sarcopenic based on the established sarcopenia algorithms. The benefits of resistance training, endurance training, power training, high-intensity interval training, multicomponent training, multidomain programs, blood flow restriction, whole-body vibration, Tai Chi, YiJinJing, and Baduanjin in people diagnosed with sarcopenia are reviewed. The most promising nutritional interventions and drug therapies in older people with sarcopenia are also discussed. Lastly, the chapter summarizes the importance of physical activity.