Incrementally builds subarrays of length i = 1, 2, ..., N of the first i elements, and at the end of each iteration, that subarray will be sorted
Ex) 4 1 2 6 3
4
4 1 -> 1 4
1 4 2 -> 1 2 4
1 2 4 6
1 2 4 6 3 -> 1 2 4 3 6 -> 1 2 3 4 6