Complex numbers are an extension of real numbers in mathematics, represented as \(a + bi\). They involve arithmetic operations like addition, subtraction, multiplication, and division. Complex numbers are typically shown in the plane, where real parts (\(a\)) lie on the x-axis and imaginary parts (\(b\)) lie on the y-axis. The modulus of a complex number is calculated using the formula \( z = |a + bi| = \sqrt{a^2 + b^2} \)