The concept of real axis and imaginary axis is complex number field. Complex number z=x+iy, where x is called the real part and y is called the imaginary part. Then the whole complex field is composed of points formed by coordinates (x, y). In the coordinate plane, the X axis is called the real axis and the Y axis is called the imaginary axis.

For example, the point (1, 0) takes 1 on the real axis and 0 on the imaginary axis, and the point is located on the X axis, corresponding to the complex number z= 1, and the imaginary part is 0, which is a real number.

The point (0, 1) is located on the imaginary axis, corresponding to the complex number z=i, and the real part is zero, which is a pure imaginary number.

Extended data:

Every point on the complex plane has a unique complex number corresponding to it, and conversely, every complex number has a unique point corresponding to it, so the complex set C is one-to-one corresponding to the set of all points on the complex plane.

The development history of complex plane;

In the17th century, the British mathematician Varis realized that the geometric representation of imaginary numbers could not be found in a straight line.

1797, Norwegian surveyor Wiezell submitted a paper "Analytical Representation of Direction, Especially Suitable for Determining Polygons on Plane and Sphere" to Danish Academy of Sciences. First of all, he proposed that complex numbers should be represented by points on the coordinate plane, established a one-to-one relationship between all complex numbers and points on the plane, and formed the concept of complex plane. But it did not attract attention at that time.

1806, a grandfather from Geneva published his paper "Imaginary Number, Its Geometric Interpretation" in Paris, and also talked about the geometric representation of complex numbers. He used the term "modulus" to represent the length of a vector, from which the term "modulus" came.