The Determinant is the numerical value of the square matrix. So, to every square matrix A = [aij] of order n, we can associate a number (real or complex) called the Determinant of the square matrix A. It is denoted by det A or |A|. (i) Read |A| as determinant A not absolute value of A. In solving a system of linear equations, Determinant plays a vital role to check whether the system of equations has a unique solution or not. Matrices chapter of Class 12 cover all the problems such as finding the Determinant of a 2×2 matrix, 3×3 matrix, evaluating the area of the triangle, finding the equation of the line using Determinant, minors, and co-factors. Also, calculating the Determinant using minor and co-factor, adjoint, and the inverse of a matrix. Besides, finding the solution of equations and Determinant as the sum of two or more determinants. Students will get to learn about the definition and meaning of determinants, remarks based on the order of determinants, properties of determinants, finding an area of a triangle using determinants, minors and co-factors of determinants, adjoint of a matrix, the inverse of the matrix, applications of determinants and matrices and various examples.