The complex plane is the plane of complex numbers spanned by the vectors 1 and , where is the imaginary number. Every complex number corresponds to a unique point in the complex plane. The line in the plane with is the real line. The complex plane is sometimes called the Argand plane or Gauss plane, and a plot of complex numbers in the plane is sometimes called an Argand diagram.
The complex plane together with the point at infinity is known as the Riemann sphere or extended complex plane and denoted or . However, the notation is also used to denote the punctured plane .