A complex conjugate is a mathematical concept used in complex numbers. If a complex number is expressed as a + bi, where a is the real part and b is the imaginary part, its complex conjugate is a - bi. This means you simply change the sign of the imaginary part. Complex conjugates are important in various fields, including engineering and physics. They are used to simplify calculations, especially when dividing complex numbers. Additionally, the product of a complex number and its conjugate results in a non-negative real number, which is useful in many mathematical applications.