Shiftless sort is a sorting algorithm that does not require any shifting of elements. It is also known as an 'IDLER' or 'donothing' sorting algorithm. This algorithm works by comparing two elements at a time and swapping them if they are out of order. The algorithm then moves on to the next pair of elements until all elements are in the correct order. This algorithm is not very efficient, but it is useful for situations where shifting elements is not possible.