What types of string formatting exist in Python?

Old formatting (%)

Uses the % operator to insert values into a string template.

name = "Alice"
age = 30
print("My name is %s and I am %d years old." % (name, age))

.format() method

A newer and more flexible way of formatting. Uses curly braces {} as placeholders.

city = "New York"
temperature = 25.5
print("The temperature in {} is {} degrees Celsius.".format(city, temperature))

f-strings (Formatted String Literals)

Introduced in Python 3.6. The most modern and recommended method. Allows embedding expressions directly in the string using the f prefix.

product = "Laptop"
price = 1200
print(f"The {product} costs ${price}.")

Template strings

Found in the string module. Less powerful but safer for working with untrusted data, as they do not execute arbitrary code in placeholders.

from string import Template

data = {'user': 'Bob'}
t = Template('Hello, $user!')
print(t.substitute(data))