Every 2 seconds someone needs blood. Your blood helps more than one life at a time. Accidents, premature babies, major surgeries require Whole blood, where your blood after testing is used directly. Trauma, Anemia, other surgeries requires only RBC, which is separated from your blood. The procedure of splitting blood components is called Cytapheresis. Similarly Platelets are used for Cancer patients undergoing Chemotherapy, Dengue fever, etc. Fresh frozen plasma is used for patients having massive Transfusions, Plasma is used for Burns and Cryoprecipitate is used for Hemophilia.
When is blood needed? Blood is needed at regular intervals and at all times as it has only a finite time to store. Red blood cells can be stored for about 42 days, Fresh Frozen Plasma and Cryoprecipitate for a year and platelets for 5 days.
Who can donate blood? Anyone above 18 years weighing more than 50kgs (110 lbs) can donate blood. At the time of donation, you should not be suffering from fever or had consumed alcohol 48 hours before or smoked during that day.