Naming variables

In Python, we can name a variable almost whatever we want. There are a few rules though:

• The name can only contain letters, numbers and the underscore character (_)
• The name cannot start with a number
• The name is not a Python keyword. These are words that the Python syntax relies on (we will see examples later).

This still leaves us with a lot of options when naming a variable. However, not all options are equally good!

As a general rule, you should try to name your variables in a meaningful, yet succinct manner. For example, let's take a look at the following code:

ucst = 2.99
q = 20
T = q * uprc

Looking at the code snippet above, does this make immediate sense to you? It is hard to understand what each variable represents, and even though the calculation is simple, we can't immediately tell what is the purpose of the code.

Now let's look at another version of the code above, but now with the variables named in a more user friendly way:

unit_cost = 2.99
quantity = 20
total_cost = quantity * unit_cost

This is much easier to understand: while the calculations are the same, we now understand that the purpose of the code is to calculate the total cost based on a quantity and a unit cost.

In addition to this principle, there are Python specific conventions on how to name different types of variables. These are not critical to understand at this stage, but a safe approach is to name your variables using lowercase letters, with different words separated by an underscore _ (for example, unit_cost).