Every two seconds, someone in the U.S. needs blood.
It's a shocking statistic—especially considering our country’s blood supply is provided entirely by volunteers. "There's no substitute for human blood," says Jim Martone, senior administrative clinical director at Northwell Health. "The voluntary blood program is supported solely by donors who come in and donate blood on a periodic or regular basis."
On some level, you probably know that blood donation is a good, important thing to do. But you may not realize exactly how this donation impacts the lives of others—or how easy it is to do. Here are five important things to know about donating blood, from best practices to surprising statistics.