This java program generates fibonacci sequence using tail recursion, since it is faster and more efficient than regular recursion. Using my variables of n, x, y, when we pick a number for n to calculate the fibonacci number, x starts at 0 and y starts at 1 respectively. As n decreases by 1 in every recursive call, x changes to y of (n + 1) and y changes to the sum of x and y of (n + 1). As this process continues, when n becomes 1, the program returns y as the answer for our fibonacci number.