The history of geocells:

The Army Corp of Engineers invented 3D geocelluar grids in the 1970's. The grid was designed for quick installation on beaches for amphibious beach assaults. It could be stored and moved in a very compact form, expanded and filled with sand, and ready at an instant for supporting vehicles, which would otherwise get stuck in the sand. The grids were also used extensively in Desert Storm. Soldiers would spread the grids out in the desert, fill cells with sand, and drive tanks and trucks on them. They would even land planes on them! The grids could easily be removed when no longer needed.
Geocells: Easy to move, quick and easy to install, and temporary, if need be.

WHY CELLS? 
There is a complex science behind geocells. Simply put, materials confined by walls are compact and therefore stronger than when they are not confined. 
If you are at the beach making a sand castle, imagine packing the bucket with sand. The sand is hard and compact. Turn the bucket over to dump that sand to build the castle, it stays intact, but is it strong? Is it hard? Without the walls it loses all strength. A continuous matrix of cells filled with any sort of confined aggregate makes an excellent foundation.
Application:

♦EARTH RETENTION 
♦LOAD SUPPORT 
♦SLOPE PROTECTION 
♦CHANNEL PROTECTION