The addition of complex numbers involves combining two or more complex numbers to produce a single complex number. This process is straightforward and follows the rule of adding the real parts together and the imaginary parts together, resulting in a new complex number expressed in the form a + bi, where a is the sum of the real parts and b is the sum of the imaginary parts. This operation is essential in various applications, particularly in fields like electrical engineering, where complex numbers are used to represent phasors.