Python Strings: The Complete Guide with Examples

Part 3 of the Python for Everyone track. Last updated: September 2026.

Strings are immutable sequences of characters — you cannot change one in place, but Python gives you a rich set of methods to build new ones. Master slicing and f-strings and 90% of string work becomes trivial.

Creating strings

s1 = "double quotes"
s2 = 'single quotes'      # identical to double quotes
s3 = """triple quotes
span multiple lines"""
raw = r"C:\new\folder"    # raw string — backslashes not treated as escapes

Indexing and slicing

s = "Python"
print(s[0])     # P      (first character)
print(s[-1])    # n      (last character — negative index counts from end)
print(s[0:3])   # Pyt    (start:stop — stop is EXCLUDED)
print(s[:3])    # Pyt
print(s[2:])    # thon
print(s[::-1])  # nohtyP (reverse!)

The slice pattern is s[start:stop:step]. Remember: stop is excluded, and negative step reverses.

Essential string methods

text = "  Hello, World!  "
print(text.strip())            # "Hello, World!" — remove surrounding whitespace
print(text.lower())            # "  hello, world!  "
print(text.upper())            # "  HELLO, WORLD!  "
print(text.replace("World", "Python"))  # "  Hello, Python!  "

csv = "a,b,c"
print(csv.split(","))          # ['a', 'b', 'c']
print("-".join(["a", "b", "c"]))  # "a-b-c"  (join is called ON the separator)

print("python".startswith("py"))  # True
print("python".endswith("on"))    # True
print("hello world".find("world"))# 6  (-1 if not found)
print("banana".count("a"))        # 3

join() is the fast, idiomatic way to build strings from lists — never concatenate in a loop.

Immutability: what it means in practice

s = "hello"
# s[0] = "H"   # TypeError! strings cannot be changed in place
s = "H" + s[1:]  # build a NEW string instead → "Hello"

Formatting recap

name, n = "Ada", 3
print(f"{name} has {n} laptops")   # f-string (preferred)
print("{} has {} laptops".format(name, n))  # older style — still seen in legacy code

Common gotchas

• strip() removes characters from both ends only, not the middle.
• find() returns -1 when missing; index() raises an error instead.
• String methods return new strings — text.upper() alone changes nothing unless you assign it.

Key takeaways

• Slice with s[start:stop:step]; stop excluded; [::-1] reverses.
• split() / join() convert between strings and lists.
• Strings are immutable — methods return new strings.
• f-strings for formatting, always.

Next in this series: Python Lists, Tuples, Sets and Dictionaries Explained.