Insertion sort: Build sorted array by inserting each element into correct position.
Left portion sorted. Take next unsorted element. Shift larger elements right. Insert.
Example [5,2,4,6,1,3]:
1. [5] sorted. Insert 2: [2,5]
2. Insert 4: [2,4,5]
3. Insert 6: [2,4,5,6]
4. Insert 1: [1,2,4,5,6]
5. Insert 3: [1,2,3,4,5,6]
Time: O(n2) worst, O(n) nearly sorted.