Python Strings: Complete Guide with Examples (2026)

Strings are one of the most widely used data types in Python. Every time you print a message, read a file, take user input, build a URL, or parse JSON, strings are working. In this guide you’ll learn all about Python strings, from the basics to formatting, methods, Unicode and best practices, with lots of examples you can run yourself.

Table of Contents

1. What is a string?
2. Creating strings
3. Escape characters and raw strings
4. Strings are immutable
5. Indexing and slicing
6. Basic operations
7. Important string methods
8. String formatting
9. Unicode, encoding and bytes
10. Comparing strings
11. A quick look at regular expressions
12. Performance tips
13. Common mistakes
14. Practice problems
15. Summary

1. What is a String in Python?

A string is an ordered sequence of Unicode characters. In Python 3 the type is called str. Strings are written inside quotes, and they are immutable, which means you cannot change them after they are created.

Python

name = "Python"
print(type(name))   # <class 'str'>
print(len(name))    # 6

2. Creating Strings

Single, double and triple quotes

Python

a = 'Hello'
b = "World"
c = """This is a
multi-line string"""
d = '''Triple single quotes
work the same way'''

print(a, b)
print(c)

Single and double quotes are identical. Use double quotes when the text contains an apostrophe, and single quotes when it contains double quotes:

Python

print("It's a nice day")
print('He said "Hello"')

Empty strings and the str() constructor

Python

empty = ""
print(len(empty))        # 0
print(bool(empty))       # False (empty strings are falsy)

print(str(123))          # '123'
print(str(3.14))         # '3.14'
print(str([1, 2, 3]))    # '[1, 2, 3]'

Taking input

Python

name = input("Enter your name: ")   # input() always returns a string
print("Hello,", name)

3. Escape Characters and Raw Strings

A backslash \ lets you insert special characters.

Escape	Meaning
\n	New line
\t	Tab
\\	Backslash
\'	Single quote
\"	Double quote
\r	Carriage return
\uXXXX	Unicode character (16-bit)

Python

print("Line 1\nLine 2")
print("Name:\tAlice")
print("She said \"Hi\"")
print("C:\\Users\\Alice")
print("\u2764")    # a heart symbol

Raw strings

Prefix a string with r and backslashes are treated literally. This is very useful for file paths and regular expressions.

Python

path = r"C:\new_folder\test"
print(path)   # C:\new_folder\test

4. Strings are Immutable

You cannot modify a string in place. Trying to do so raises an error:

Python

s = "hello"
s[0] = "H"    # TypeError: 'str' object does not support item assignment

Instead, create a new string:

Python

s = "hello"
s = "H" + s[1:]
print(s)      # Hello

Because strings are immutable, they can be used as dictionary keys and set elements.

5. Indexing and Slicing

Indexing

Each character has a position (index). Counting starts at 0 from the left, and at -1 from the right.

Python

s = "PYTHON"
#    P  Y  T  H  O  N
#    0  1  2  3  4  5
#   -6 -5 -4 -3 -2 -1

print(s[0])     # P
print(s[3])     # H
print(s[-1])    # N
print(s[-3])    # H
print(s[10])    # IndexError: string index out of range

Slicing

The syntax is string[start:stop:step]. The stop index is not included.

Python

s = "PYTHON"
print(s[0:3])     # PYT
print(s[:3])      # PYT
print(s[3:])      # HON
print(s[1:5])     # YTHO
print(s[::2])     # PTO   (every 2nd character)
print(s[::-1])    # NOHTYP (reversed)
print(s[-3:])     # HON
print(s[:-1])     # PYTHO
print(s[2:100])   # THON  (slices never raise IndexError)

6. Basic Operations

Concatenation and repetition

Python

first = "Hello"
second = "World"
print(first + " " + second)   # Hello World
print("ab" * 3)               # ababab
print("-" * 20)               # --------------------

# You cannot add a string and a number directly:
# print("Age: " + 25)         # TypeError
print("Age: " + str(25))      # Age: 25

Length and membership

Python

s = "Python programming"
print(len(s))              # 18
print("Python" in s)       # True
print("Java" in s)         # False
print("Java" not in s)     # True

Looping through a string

Python

for ch in "abc":
    print(ch)

for i, ch in enumerate("abc"):
    print(i, ch)

7. Important String Methods

Every string method returns a new string; the original never changes.

Case methods

Python

s = "hello World"
print(s.upper())        # HELLO WORLD
print(s.lower())        # hello world
print(s.title())        # Hello World
print(s.capitalize())   # Hello world
print(s.swapcase())     # HELLO wORLD
print("Straße".casefold())  # strasse (best for case-insensitive comparison)

Searching

Python

s = "banana"
print(s.find("an"))        # 1
print(s.find("xyz"))       # -1  (not found)
print(s.index("an"))       # 1
# s.index("xyz")           # ValueError
print(s.rfind("an"))       # 3   (search from the right)
print(s.count("a"))        # 3
print(s.startswith("ban")) # True
print(s.endswith("na"))    # True

Tip: find() returns -1 when nothing is found, while index() raises a ValueError.

Removing whitespace

Python

s = "   hello   "
print(repr(s.strip()))    # 'hello'
print(repr(s.lstrip()))   # 'hello   '
print(repr(s.rstrip()))   # '   hello'
print("xxhixx".strip("x"))   # hi

Replacing

Python

s = "I like cats. Cats are great."
print(s.replace("Cats", "dogs"))     # I like cats. dogs are great.
print("aaaa".replace("a", "b", 2))   # bbaa  (only first 2)

split() and join()

Python

text = "apple,banana,cherry"
fruits = text.split(",")
print(fruits)                  # ['apple', 'banana', 'cherry']

print("a b   c".split())        # ['a', 'b', 'c']  (splits on any whitespace)
print("a-b-c-d".split("-", 2))  # ['a', 'b', 'c-d']

print(" | ".join(fruits))       # apple | banana | cherry
print("".join(["a", "b", "c"])) # abc

lines = "one\ntwo\nthree".splitlines()
print(lines)                    # ['one', 'two', 'three']

print("key=value=x".partition("="))   # ('key', '=', 'value=x')

Checking content

Method	Returns True if...	Example
isalpha()	all characters are letters	"abc".isalpha() → True
isdigit()	all characters are digits	"123".isdigit() → True
isalnum()	letters or digits only	"abc123".isalnum() → True
isspace()	only whitespace	" ".isspace() → True
isupper()	all cased letters are uppercase	"ABC".isupper() → True
islower()	all cased letters are lowercase	"abc".islower() → True
istitle()	title-cased	"Hello World".istitle() → True

Note that all of these return False for an empty string.

Alignment and padding

Python

print("hi".center(10, "*"))   # ****hi****
print("hi".ljust(6, "."))      # hi....
print("hi".rjust(6, "."))      # ....hi
print("42".zfill(5))           # 00042

Other useful methods

Python

print("a\tb".expandtabs(4))               # a   b
print("hello".removeprefix("he"))          # llo   (Python 3.9+)
print("hello.py".removesuffix(".py"))      # hello (Python 3.9+)

table = str.maketrans("abc", "123")
print("aabbcc".translate(table))           # 112233

8. String Formatting

Python offers three ways to put values inside strings. The modern and recommended way is f-strings.

a) f-strings (Python 3.6+)

Python

name = "Alice"
age = 30
print(f"My name is {name} and I am {age} years old.")
print(f"Next year I will be {age + 1}.")
print(f"{name.upper()} has {len(name)} letters.")

# Debugging shortcut (3.8+)
x = 10
print(f"{x = }")        # x = 10

Format specifiers

Python

pi = 3.14159265
print(f"{pi:.2f}")          # 3.14
print(f"{1234567:,}")       # 1,234,567
print(f"{0.256:.1%}")       # 25.6%
print(f"{42:05d}")          # 00042
print(f"{255:b}")           # 11111111  (binary)
print(f"{255:x}")           # ff        (hex)
print(f"{255:#o}")          # 0o377     (octal)
print(f"{1500000:e}")       # 1.500000e+06

# Width and alignment
print(f"[{'left':<10}]")    # [left      ]
print(f"[{'right':>10}]")   # [     right]
print(f"[{'mid':^10}]")     # [   mid    ]
print(f"[{'pad':*^11}]")    # [****pad****]

b) The format() method

Python

print("Hello, {}!".format("Bob"))
print("{0} {1} {0}".format("a", "b"))          # a b a
print("{name} is {age}".format(name="Eve", age=25))
print("{:.3f}".format(2.71828))                # 2.718

c) The % operator (old style)

Python

print("Hello, %s! You are %d years old." % ("Sam", 22))
print("Pi is about %.2f" % 3.14159)

You will still see this in older code, but prefer f-strings in new code.

Template strings

Python

from string import Template
t = Template("Hello, $name!")
print(t.substitute(name="World"))

Template strings are handy when the format string comes from users, because they are safer than format() with untrusted input.

9. Unicode, Encoding and Bytes

Python 3 strings are Unicode, so they can hold text from any language and emojis.

Python

s = "नमस्ते 😀"
print(len(s))            # 8

print(ord("A"))          # 65
print(chr(65))           # A
print(chr(0x1F600))      # 😀

Encoding and decoding

str is text; bytes is raw data. Convert between them with encode() and decode().

Python

text = "café"
data = text.encode("utf-8")
print(data)                    # b'caf\xc3\xa9'
print(len(text), len(data))    # 4 5
print(data.decode("utf-8"))    # café

# Handling errors
print("café".encode("ascii", errors="ignore"))   # b'caf'
print("café".encode("ascii", errors="replace"))  # b'caf?'

Always specify encoding="utf-8" when reading or writing text files:

Python

with open("notes.txt", "w", encoding="utf-8") as f:
    f.write("Hello, world")

10. Comparing Strings

Python

print("apple" == "apple")    # True
print("apple" == "Apple")    # False (case-sensitive)
print("apple" < "banana")    # True  (compared by Unicode code points)
print("a" < "B")             # False ('a' = 97, 'B' = 66)

# Case-insensitive comparison
print("Python".casefold() == "PYTHON".casefold())   # True

== vs is

== compares values. is checks whether two names point to the same object. Always use == to compare strings.

Python

a = "hello world"
b = "".join(["hello", " world"])
print(a == b)    # True
print(a is b)    # usually False; do not rely on this

Sorting strings

Python

words = ["banana", "Apple", "cherry"]
print(sorted(words))                  # ['Apple', 'banana', 'cherry']
print(sorted(words, key=str.lower))   # ['Apple', 'banana', 'cherry']
print(sorted(words, key=len))         # ['Apple', 'banana', 'cherry']

11. A Quick Look at Regular Expressions

For complex pattern matching, use the built-in re module.

Python

import re

text = "Contact: alice@example.com, bob@test.org"
emails = re.findall(r"[\w.]+@[\w.]+\.\w+", text)
print(emails)    # ['alice@example.com', 'bob@test.org']

print(re.sub(r"\d+", "#", "Room 101, Floor 4"))   # Room #, Floor #

m = re.search(r"(\d{3})-(\d{4})", "Call 555-1234")
if m:
    print(m.group(1), m.group(2))   # 555 1234

12. Performance Tips

• Use join() to build large strings. Repeated += in a loop can be slow because a new string is created each time.

Python

# Slow for large loops
result = ""
for i in range(1000):
    result += str(i)

# Better
result = "".join(str(i) for i in range(1000))

• Use in for simple membership checks instead of find().
• Prefer f-strings, they are the fastest formatting option.
• Use io.StringIO if you need a mutable, file-like text buffer.

13. Common Mistakes

1. Expecting methods to change the string.
   Python

   s = "hello"
   s.upper()          # result is thrown away
   print(s)           # hello
   s = s.upper()      # correct
   print(s)           # HELLO

2. Mixing strings and numbers. "5" + 5 raises a TypeError; use int("5") + 5 or "5" + str(5).
3. Forgetting that input() returns a string. Convert with int() or float().
4. Using is instead of == for comparing text.
5. Off-by-one slicing errors. Remember that the stop index is excluded.
6. Backslashes in Windows paths. Use raw strings or forward slashes.

14. Practice Problems

Problem 1: Check for a palindrome

Python

def is_palindrome(s):
    cleaned = "".join(ch.lower() for ch in s if ch.isalnum())
    return cleaned == cleaned[::-1]

print(is_palindrome("A man, a plan, a canal: Panama"))   # True
print(is_palindrome("Hello"))                            # False

Problem 2: Count vowels

Python

def count_vowels(s):
    return sum(1 for ch in s.lower() if ch in "aeiou")

print(count_vowels("Python Programming"))   # 4

Problem 3: Word frequency

Python

from collections import Counter

text = "the cat and the hat and the bat"
freq = Counter(text.split())
print(freq)                   # Counter({'the': 3, 'and': 2, 'cat': 1, 'hat': 1, 'bat': 1})
print(freq.most_common(1))    # [('the', 3)]

Problem 4: Check for an anagram

Python

def is_anagram(a, b):
    return sorted(a.lower()) == sorted(b.lower())

print(is_anagram("Listen", "Silent"))   # True

Problem 5: Reverse each word

Python

s = "hello world"
print(" ".join(w[::-1] for w in s.split()))   # olleh dlrow

Problem 6: Caesar cipher

Python

def caesar(text, shift):
    result = []
    for ch in text:
        if ch.isalpha():
            base = ord("A") if ch.isupper() else ord("a")
            result.append(chr((ord(ch) - base + shift) % 26 + base))
        else:
            result.append(ch)
    return "".join(result)

print(caesar("Hello, World!", 3))    # Khoor, Zruog!

15. Summary and Cheat Sheet

Task	Use
Length	len(s)
Slice / reverse	s[a:b], s[::-1]
Change case	upper(), lower(), title()
Search	find(), index(), count(), in
Clean	strip(), replace()
Split / combine	split(), join()
Validate	isdigit(), isalpha(), isalnum()
Format	f-strings: f"{value:.2f}"
Bytes	encode(), decode()

Key points to remember:

• Strings are immutable sequences of Unicode characters.
• Indexing starts at 0; negative indexes count from the end.
• String methods return new strings; assign the result to keep it.
• Use f-strings for formatting and join() for building large strings.
• Use raw strings for regex patterns and Windows paths.
• Always specify UTF-8 encoding when working with files.

That covers everything you need to work confidently with strings in Python. Try the practice problems, experiment in the Python shell, and you will master strings quickly. If you found this guide useful, share it and leave a comment with your questions!

Frequently Asked Questions (FAQ)

What is a string in Python?

A string is an immutable sequence of Unicode characters, represented by the str type and written inside single, double, or triple quotes.

Are strings mutable in Python?

No. Strings are immutable. Methods like upper() or replace() return a new string instead of changing the original.

How do I reverse a string in Python?

Use slicing: s[::-1].

What is the best way to format strings in Python?

f-strings (Python 3.6+), for example f"Hello, {name}". They are readable and fast.

How do I check if a string contains a substring?

Use the in operator: "cat" in "concatenate" returns True.

What is the difference between find() and index()?

find() returns -1 when the substring is missing, while index() raises a ValueError.

How do I convert a string to an integer?

Use int("42"). Wrap it in try/except ValueError if the input may not be numeric.

Next up: Python Lists, Tuples and Dictionaries.