Blind nailing is the process of forcing nails into the grooves of any type of tongue and groove piece material, particularly tongue and groove wood flooring.
The nail is sent into the groove at roughly a 45 degree angle. The nail can be started with a normal carpenter's hammer, and then made flush with the surface of the groove by means of a nailset.
In the case of wooden flooring, the nail is usually forced into the groove and made flush in one blow by means of a pneumatic or electric flooring hammer or stapler. Most flooring material, even soft woods such as pine, are too hard to nail by hand.
Contrast blind nailing with face nailing, which is done on the last row of floorboards.