This is a process of substituting and placing values of a variable in certain points in a string. This process is used to insert specified value(s) into a string at specific points, whereby these points can be specified depending on the chosen method of approach which we shall see soon.
The importance of interpolating variables into strings is that, in as much as you can possibly achieve the same output of interpolating strings with concatenation. Concatenation is clumsy and you need the readability and flexibility that interpolation provides.
Prior to Python 3.6, we had two ways of interpolation: %-formatting and str.format(). However, as from Python v3.6, the f-string was introduced and it provides a better and more prominent way to interpolate.