The sheet is one of the three basic structures in FoldIt. In its ideal form, it appears as a lightning-shaped flat strip of amino acids with sidechains coming out of the faces in alternating directions--up and down. The main attribute of sheets is that they readily form multiple hydrogen bonds with neighboring sheets. For this reason, they are the only structure for which hydrogen bonds can be seen. By changing other structure types to sheets temporarily, a great deal of information about the bonding of a structure can be seen.

See http://en.wikipedia.org/wiki/Beta_sheet