It is often advantageous to have an orientation system available on the drawing plane. Imagine two straight lines that are perpendicular to one another. Imagine a plane with one line horizontal and the other vertical. By this we mean that the axes run without boundary "to infinity" (even though we can, of course, only draw a section of the plane of finite size). The two axes intersect one another in a point called zero point or origin.

Tip: Even though the designations x and y are frequently used (referring to an xy coordinate system), it is not compulsory. Any other alphabets could be used. If the coordinates are, for example, called r and, we refer to an r axis and an s axis (the first one is called abscissa and the second one ordinate) or to an rs coordinate system, and, apart from that, everything would be exactly as described here.