A merge sort breaks down an array into smaller arrays and these smaller arrays are merged in pairs until it is rebuilt into order.
Firstly the array needs to be broken down into individual values. The values are then paired into arrays, and ordered correctly in these new arrays. These arrays are then paired and their values are placed into the correct order. This process is repeated until all the numbers are in order within one array.
Merge sort is more efficent than a bubble sort when used on larger arrays, however the process is not as simple as with a bubble sort.