漫画：插入排序是什么？

public static int[] insertionSort(int[] array){
    if (array.length == 0) return array;
    int current;
    for(int i =0;i<array.length-1;i++){
        current = array[i+1];
        int preindex = i;
        while(preindex >= 0 && array[preindex] > current){
            array[preindex +1] = array[preindex];
            preindex--;
        }
        array[preindex+1] = current;
    }
    return array;
}