© 2015 Elsevier Inc. All rights reserved. CKD is defined as abnormalities of kidney structure or function, present for at least 3 months. In both the original National Kidney Foundation Kidney Disease Outcomes Quality Initiative (NKF-KDOQI) guidelines and the Kidney Disease Improving Global Outcomes (KDIGO) 2012 updated guidelines, CKD is defined by a glomerular filtration rate<60mL/min/1.73m2 or urinary albumin:creatinine ratio (ACR)≥30mg/g (≥3mg/mmol). In studies from several world regions, the prevalence of estimated GFR<60ml/min/1.73m2 has often exceeded 10%. Additionally, the prevalence of proteinuria in many of these studies exceeded 5%. Although ESRD is the most commonly recognized outcome for patients with CKD, CKD is associated with an increased risk for several other outcomes, including subsequent risk of all-cause and cardiovascular mortality, AKI, stroke, heart failure, peripheral arterial disease, atrial fibrillation, infection-related hospitalization and mortality, cancer, frailty, and decline in functional status. The prevalence of CKD increases with age and is higher among blacks compared to whites in the US. Major risk factors for CKD include hypertension, diabetes and the metabolic syndrome. Although clearly challenging, public health efforts are needed to reduce the burden of CKD and its adverse outcomes.