It is a word that you normally do not hear, but hairdressers use it to set hair every day. Protein structures of the hair are held together by chemical bonds called hydrogen bonds.
When the hair is wet the bonding separates but solidifies the moment it gets dry. Using hairdryers, curling irons all create the same effect  but damages the hair if not done correctly.
In other words, while the hair is wet no styling can be done and when it dries completely stylings will hold. If you apply heat too much at this point the protein in the hair gets damaged.
The solution to this problem is using hydrogen bond. The hair can then be set without damaging the hair. The point is to not dry the hair completely and style the hair precisely while the hair is slightly damp and then dry it.
The following pictures are good examples for stylings. Even a small rubber band and air-dry can create nice waves using Hydrogen Bond.