Tongue and groove is a method of fitting similar objects together, edge to edge, used mainly with wood, in flooring, parquetry, panelling, and similar constructions. Tongue and groove connections allow two flat pieces to be connected securely together to form a single flat surface.
 
 
 
The tongue on the flooring is the short flat edge on one side of the board, this is the top edge that is going to angle and secure into the bottom side of another board.
 
 
 
Tongue and groove flooring is a type of flooring that uses the most conventional joining process; The tongue and groove format is the most cost-efficient fitting method, a great deal cheaper than the newer and more sophisticated "click" system, which is one of the main purposes that it is more commonly used. Because it is the most common installation method, there are also far more types of wood available with tongue and groove.