None

Syntax

variable = None

Examples

user = None
print(user)  # None

# Later in the program, assign a real value
user = "Alice"
print(user)  # Alice

def greet(name=None):
    if name is None:
        print("Hello, stranger!")
    else:
        print(f"Hello, {name}!")

greet()          # Hello, stranger!
greet("Priya")   # Hello, Priya!

result = None

if result is None:
    print("No result yet")

data = {"name": "Fola"}
value = data.get("age")  # key doesn't exist

if value is not None:
    print(f"Age: {value}")
else:
    print("Age not provided")

def log_message(msg):
    print(f"LOG: {msg}")
    # no return statement

result = log_message("Server started")
print(result)  # None

Best practices

• Always use 'is None' or 'is not None' rather than '== None', since None is a singleton and identity comparison is both faster and more correct
• Use None as a default argument for optional parameters instead of mutable defaults like [] or {}, which are evaluated only once and shared across calls
• Remember that dict.get() returns None by default when a key is missing, rather than raising an error like square-bracket access does
• Don't confuse None with False, 0, or an empty string/list - they are all falsy in a boolean context but are not the same value
• Use None to represent "not yet known" or "not applicable", and reserve empty collections for "known to be empty"

At a glance

Purpose

Scripting and general-purpose applications

File extension

.py

Runs in

Python interpreter

Usually used with

Python standard library and packages

Specifications & further reading

• Python language reference

Related Python documentation