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Python Variable Names

A variable name is the label that identifies a variable. Names use only letters, digits, and underscores.

Letters, digits, and underscores

These names are all legal.

user_name = "Kai"
user_age2 = 14
print(user_name)
print(user_age2)

Never start with a digit

A digit can appear later in the name.

# 2score = 10 is not allowed
score2 = 10
print(score2)

Case makes a new variable

Small and capital letters mean different names.

age = 12
Age = 20
print(age)
print(Age)

Keywords are not allowed

The word class is reserved. Add a word to make a legal name.

class_name = "art"
print(class_name)

Example

first_name = "Lena"
lucky_number = 7
favorite_color = "green"
print(first_name)
print(lucky_number)
print(favorite_color)

Key points

  • Use only letters, digits, and underscores in a name
  • A variable name identifies one variable in code.
  • A name cannot start with a digit
  • snake_case: join words with underscores, like first_name
  • Names are case sensitive, so age and Age differ
  • Keyword: a word Python reserves for its own use
  • Use descriptive names so the meaning stays clear
  • Readers expect snake_case.

In this example, first_name stores text. The name uses snake_case. Next, lucky_number stores a whole number. Then favorite_color stores another text value. Each print shows one well-named value.

Note

snake_case is a shared habit, not a Python rule.

Python accepts other styles.

Try it Yourself

Edit the code, then press Run.

Running is simulated · Python Playground

Exercise

Which one is a legal variable name?