Let's try to write a program that inputs two numbers and prints their sum. We read the two numbers and store them in the variables a and b using the assignment operator $=.$ On the left side of an assignment operator we put the name of the variable. The name could be a string of latin characters $($A$-$Z$,$ a$-$z$,0-9,\_)$ but must start with a letter in the range A$-$Z or a$-$z$.$ On the right side of an assignment operator we put any expression that Python can evaluate. The name starts pointing to the result of the evaluation. Read this example, run it and look at the output: