Kidney failure, also known as renal failure, occurs when the kidneys can no longer filter waste and excess fluids from the blood effectively. This can lead to a buildup of harmful substances in the body, causing various health issues. There are two main types: acute kidney failure, which happens suddenly, and chronic kidney failure, which develops gradually over time. Symptoms of kidney failure may include fatigue, swelling in the legs and ankles, and changes in urination. Treatment options vary and can include medications, dietary changes, and in severe cases, dialysis or a kidney transplant to restore kidney function.