InDesign tutorial: Using the Liquid Layout panel | lynda.com

Alternate layouts and  Liquid Layout Design:It is process/tool through which automatically or semi-automatically you  design layout for multiple page sizes, orientations, or aspect ratios

                       The toll and process can save you hours of reworking the same content into different layouts, page sizes, and orientations.

More Liquid/Alternate Layout Tutorials

http://www.creativepro.com/article/indesign-how-using-liquid-layout

http://www.adobe.com/inspire/2013/02/alternate-layouts-indesign.html