Python makes it easy to sort lists using built-in methods. Lists can be sorted in ascending or descending order, either in-place or by returning a new list.

You can sort numbers, strings, or even custom objects using sort() or sorted().

List for Reference

numbers = [4, 2, 9, 1, 5]
fruits = ["banana", "apple", "cherry"]

1. sort() – Sort the List In-Place

The list.sort() method sorts the list permanently, modifying the original list.

Example 1: Sort Numbers (Ascending)

numbers = [4, 2, 9, 1, 5]
numbers.sort()
print(numbers)

Output:

[1, 2, 4, 5, 9]

Example 2: Sort Strings (Alphabetically)

fruits = ["banana", "apple", "cherry"]
fruits.sort()
print(fruits)

Output:

['apple', 'banana', 'cherry']

2. sorted() – Return a New Sorted List

The sorted() function returns a new sorted list, leaving the original unchanged.

Example:

numbers = [4, 2, 9, 1, 5]
sorted_numbers = sorted(numbers)
print("Original:", numbers)
print("Sorted:", sorted_numbers)

Output:

Original: [4, 2, 9, 1, 5]
Sorted: [1, 2, 4, 5, 9]

Great when you need to keep the original list intact.

3. Sort in Descending Order

Use reverse=True with either sort() or sorted().

Example:

numbers = [4, 2, 9, 1, 5]
numbers.sort(reverse=True)
print(numbers)

Output:

[9, 5, 4, 2, 1]

4. Custom Sort with key=

You can customize sorting using the key parameter, such as sorting by length, last character, etc.

Example: Sort Strings by Length

fruits = ["banana", "apple", "kiwi", "cherry"]
fruits.sort(key=len)
print(fruits)

Output

['kiwi', 'apple', 'banana', 'cherry']

5. Sort Case-Insensitive

By default, Python considers uppercase before lowercase in ASCII. Use str.lower to sort case-insensitively.

Example:

names = ["Alice", "bob", "Charlie", "anna"]
names.sort(key=str.lower)
print(names)

Output:

['Alice', 'anna', 'bob', 'Charlie']

Summary of Sort Methods

Things to Remember

• sort() works only on lists
• sorted() works on any iterable (lists, tuples, strings, etc.)
• Don't use sort() on mixed-type lists (e.g., integers and strings)