We study the multiple-strip packing problem, in which the goal is to pack all the rectangles into m vertical strips of unit widths such that the maximum height among strips used is minimized. A number of on-line algorithms
for this problem are proposed, in which the decision of delivering the rectangles to strips as well as packing the rectangles
in strips must be done on-line. Both randomized and deterministic on-line algorithms are investigated, and all of them are
guaranteed to have constant competitive ratios.