Definition
The Fibonacci sequence (xn = xn-1 + xn-2) is a series of numbers, in which a new number is formed when the two before it are added. It starts with 0 and 1, and continues to go on like 0,1,1,2,3,5,8,13,21 and so forth.
Origin
It is named after Fibonacci, and was first introduced in his Liber abaci in 1202. He was born to Pisan merchants and had a wide ranging aptitude for Mathematics and travelling the world.
Further Reading