A square matrix is a type of matrix that has the same number of rows and columns. For example, a 2x2 matrix has 2 rows and 2 columns, while a 3x3 matrix has 3 rows and 3 columns. Square matrices are often used in various mathematical applications, including solving systems of equations and performing transformations in geometry. One important property of square matrices is that they can have a determinant, which is a special number that provides information about the matrix, such as whether it is invertible. Additionally, square matrices can be classified as symmetric, diagonal, or identity matrices, each with unique characteristics and uses in linear algebra.