Yitang Zhang is an American mathematician in the field of number theory. He was a relatively unknown math professor at the University of New Hampshire when he showed there are an infinite number of prime pairs whose difference is less than 70 million. This finding is remarkable because it was the first step towards proving the conjecture that there are an infinite number of prime pairs with smaller differences. His work led to a MacArthur fellowship and an appointment as a professor at the University of California, Santa Barbara.
I enjoyed watching this video by Numberphile explaining his work as I prepared to talk about him in my Algebra class.