Dialysis is a medical treatment that cleans your blood when your kidneys can't do it themselves. Your kidneys are like the body's filtration system, removing waste and extra water from your blood every day. When kidneys fail or stop working properly, waste builds up in the body and makes people very sick. That's when dialysis becomes necessary.

During dialysis, a special machine does the job your kidneys normally do. The most common type is hemodialysis, where blood flows out of your body through a tube, passes through a filter that removes waste and excess fluid, and then flows back into your body. Each session takes several hours, and most people need dialysis three times a week.

Another type, peritoneal dialysis, uses the lining of your abdomen as a natural filter instead of a machine. A special fluid is put into your belly, where it absorbs waste from your blood, then gets drained out and replaced with fresh fluid.

Dialysis keeps people alive when their kidneys fail, but it's demanding. Patients spend many hours each week connected to machines or doing treatments at home. Many people on dialysis hope for a kidney transplant, which can free them from needing these regular treatments. Medical scientists continue working to make dialysis more convenient and effective for the hundreds of thousands of people who depend on it.