Python Variables, Data Types and Operators with Examples

Part 2 of the Python for Everyone track. Last updated: September 2026.

Python is dynamically typed: you never declare a variable's type — the interpreter figures it out from the value. This makes code short, but means you should understand exactly what types exist and how they behave.

Variables: the rules

name = "Ada"        # no type declaration needed
age = 36
pi = 3.14159
is_active = True
nothing = None      # Python's "null"

# Naming rules: letters, digits, underscore; cannot start with a digit
# Convention: snake_case for variables and functions
user_name = "grace"

Use type() to inspect any value: type(age) returns <class 'int'>.

The core data types

• int — whole numbers, any size: 10, -3, 10**100 (no overflow!)
• float — decimals: 3.14, -0.5, 2.0
• str — text in quotes: "hello", 'hello'
• bool — True / False (capital T/F)
• None — the absence of a value (like null)

Type conversion

int("42")        # 42
float("3.14")    # 3.14
str(100)         # "100"
bool(0)          # False — 0, "", [], None are all falsy
bool("hello")    # True

Watch out: "5" + 3 raises TypeError. Python will not silently mix strings and numbers — convert explicitly.

Operators

# Arithmetic
print(7 / 2)    # 3.5  (true division — always float)
print(7 // 2)   # 3    (floor division)
print(7 % 2)    # 1    (remainder)
print(2 ** 10)  # 1024 (power)

# Comparison — result is always a bool
print(5 == 5)   # True
print(5 != 3)   # True
print(4 <= 4)    # True

# Logical
print(True and False)  # False
print(True or False)   # True
print(not True)        # False

# Assignment shortcuts
x = 10
x += 5   # x is now 15 (also -=, *=, /=, //=, %=, **=)

f-strings: the modern way to build strings

name = "Ada"
score = 95.5
print(f"{name} scored {score}")        # Ada scored 95.5
print(f"{score:.1f}")                 # 95.5 — one decimal place
print(f"{name!r}")                    # 'Ada' — with quotes (debug-friendly)

Prefer f-strings over concatenation and .format() — they are faster to write and easier to read.

Key takeaways

• No type declarations — but every value still has a type; check with type().
• / always gives a float; // floors; ** is power.
• Convert explicitly: int(), float(), str(), bool().
• Use f-strings for all string building.

Next in this series: Python Strings: The Complete Guide with Examples.