Apheresis is a medical procedure that involves taking certain components out of your blood and then putting the rest back in your body. Think of it like a filter. A machine is used that takes a small amount of your blood and it separates the components like red blood cells, platelets, or plasma from your blood. Then, the parts that are taken out are used for medical treatments, and the rest is put back into your body. This helps people who need special treatments for conditions like cancer and autoimmune diseases.