A **square matrix** is a [[matrix]] which has the same number of rows and columns. The matrix $A\in F^{n\times n}$ is *square* $ \left(\begin{array}{rrr}1 & 6 & 2 \\ -9 & 0 & 3 \\ 2 & 4 & 8\end{array}\right) $ There are lots of special square matrices: [[symmetric matrix]] [[diagonal matrix]] [[identity matrix]]