meaning of bubble sorting code example

Example: bubble sort integers

for (int i = 0; i < n-1; i++) 
            for (int j = 0; j < n-i-1; j++) 
                if (arr[j] > arr[j+1]) 
                { 
                    // swap arr[j+1] and arr[i] 
                    int temp = arr[j]; 
                    arr[j] = arr[j+1]; 
                    arr[j+1] = temp; 
                }