Chronic Kidney Disease is a progressive loss of kidney function over time. It's typically categorized into different stages based on the glomerular filtration rate (GFR), with the severity increasing from stage 1 to stage 5, where stage 5 is end-stage renal disease. Common causes include diabetes and high blood pressure. Symptoms might include fatigue, fluid retention, changes in urine output, and difficulty sleeping. Management often focuses on controlling the underlying causes and may involve lifestyle changes, medication, and in later stages, dialysis or a kidney transplant.