Python Variables
Variables are containers for storing data values.
Creating Variables
Python has no command for declaring a variable. A variable is created the moment you first assign a value to it.
Example
x = 5
y = "Hello, World!"
print(x)
print(y)
Variables do not need to be declared with any particular type and can even change type after they have been set.
Example — Changing type
x = 4 # x is an integer
x = "Sally" # x is now a string
print(x)
Variable Names (Rules)
A variable can have a short name (like x) or a more descriptive name (age, total_price). Rules:
- Must start with a letter or underscore
_ - Cannot start with a number
- Can only contain letters, numbers, and underscores (A–Z, 0–9, _)
- Variable names are case-sensitive (
age,AgeandAGEare different)
Example — Legal variable names
myvar = "John"
my_var = "John"
_my_var = "John"
myVar = "John"
MYVAR = "John"
myvar2 = "John"
Assign Multiple Values
Python allows you to assign values to multiple variables in one line:
Example — Many values to many variables
x, y, z = "Orange", "Banana", "Cherry"
print(x)
print(y)
print(z)
You can also assign the same value to multiple variables:
Example — One value to many variables
x = y = z = "Orange"
print(x)
print(y)
print(z)
Output Variables
Use the print() function to output variables. You can combine text and variables using + or an f-string (recommended):
Example — f-strings (modern way)
name = "Alice"
age = 25
print(f"My name is {name} and I am {age} years old.")
Global Variables
Variables created outside of a function are called global variables and can be used by everyone, both inside and outside of functions.
Example — Global vs Local
x = "awesome" # global variable
def my_function():
print("Python is " + x)
my_function()
print("Python is " + x)
✅ Best Practice
Use snake_case for variable names:
user_name, total_price, is_active. This is the Python convention (PEP 8).