Science's Breakthrough of the Year

Every December, Science magazine announces a Breakthrough of the Year and a short list of runners-up. Writers and editors, with help from the Board of Reviewing Editors and other scientists, comb through the year’s scientific advances and judge which have done the most to benefit humanity, answer long-standing questions, or pave the way for fruitful new research. It’s a tricky task. Many discoveries take years to catch fire; others seem exciting but never fulfill their promise. And even when something big happens in science, it’s not always obvious exactly when and where the “breakthrough” took place. With those caveats in mind, here are our annual lists of science’s greatest hits.