By Profile
All wood flooring profiles use the tongue and groove (T&G) approach for installation to achieve the best possible fit. Flooring made of engineered wood is often glueless - the pieces simply click together, or sometimes also require the use of staples or glue during installation.
T&G flooring profiles are described as such because on one side of the board there is what looks like a tongue sticking out, while on the opposite side there is a groove. Installation of the wood flooring is made easier as you simply have to fit and click the tongue and groove parts of the boards together.