Have you ever looked at a messy list of numbers or words and wished there was a simple way to clean it up? Python makes that easy. Sorting a list isn’t just about making things look neat. It often helps improve search performance, find duplicates, or clean data before you process it. When you're working with a list in Python—whether it’s a list of names, prices, or scores—the sort() method is your go-to tool to rearrange things in order.

It's built into every list object, and it doesn't need any fancy setup. This method works in place, so it changes the list directly without making a new one. This guide will break down everything you need to know about sorting lists in Python using sort(), from basic to more advanced sorting tricks.

How to Use the Python sort() Method to Sort Lists?

Using the Basic sort() Method

The sort() method is called directly on a list and, by default, sorts it in ascending order. Here's a basic example:

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numbers = [4, 1, 3, 9, 2]

numbers.sort()

print(numbers)

# Output: [1, 2, 3, 4, 9]

The original list is updated, and the numbers are now sorted. It doesn't need to be assigned to a new variable unless you also want the old order. If you wish to create a new list, use the built-in sorted() function instead.

Sorting in Reverse Order

If you want your list in descending order, pass reverse=True to sort().

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numbers = [4, 1, 3, 9, 2]

numbers.sort(reverse=True)

print(numbers)

# Output: [9, 4, 3, 2, 1]

This is useful for leaderboard scores or price listings where you want the biggest value first.

Sorting Strings Alphabetically

You can sort strings just as easily. By default, it sorts by Unicode values, which means uppercase letters come before lowercase ones.

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words = ["banana", "Apple", "cherry"]

words.sort()

print(words)

# Output: ['Apple', 'banana', 'cherry']

Notice how "Apple" comes before "banana" because capital letters are smaller in Unicode.

Sorting with Lowercase Comparison

If you want a case-insensitive sort, you can use a key function. The key argument lets you define a rule for sorting.

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words = ["banana", "Apple", "cherry"]

words.sort(key=str.lower)

print(words)

# Output: ['Apple', 'banana', 'cherry']

Now it sorts everything as if it were lowercase, which feels more natural.

Sorting Lists of Tuples by Index

If your list has tuples, you can sort by a specific element in each tuple. Let’s say you have a list of students with their scores.

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students = [("John", 82), ("Emma", 91), ("Alex", 78)]

students.sort(key=lambda x: x[1])

print(students)

# Output: [('Alex', 78), ('John', 82), ('Emma', 91)]

This sorts the list by the second item in each tuple, which is the score.

Sorting Custom Objects

If you're working with objects, you can sort them by attributes. Suppose you have a class like this:

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class Product:

def __init__(self, name, price):

self.name = name

self.price = price

items = [Product("Pen", 1.5), Product("Notebook", 3.0), Product("Pencil", 0.5)]

items.sort(key=lambda x: x.price)

for item in items:

print(item.name, item.price)

# Output:

# Pencil 0.5

# Pen 1.5

# Notebook 3.0

This is one of the most practical uses of sort() in real-world applications like e-commerce or databases.

Using key=len to Sort by Length

You can sort lists by length, too. This is useful when dealing with strings or sublists.

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names = ["Anna", "Elizabeth", "Tom", "Catherine"]

names.sort(key=len)

print(names)

# Output: ['Tom', 'Anna', 'Elizabeth', 'Catherine']

Shortest names come first. You can combine this with reverse=True to get the longest first.

Combining key and reverse

If you want more control, combine the key and reverse options. For example, sort by string length in descending order:

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names = ["Anna", "Elizabeth", "Tom", "Catherine"]

names.sort(key=len, reverse=True)

print(names)

# Output: ['Catherine', 'Elizabeth', 'Anna', 'Tom']

This gives you full control over how your list is arranged.

Sorting Lists with Mixed Types

You might think of mixing strings and numbers in one list. It can lead to errors:

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mixed = [1, "two", 3]

mixed.sort()

# Output: TypeError: '<' not supported between instances of 'str' and 'int'

The sort() method can’t compare different types unless you manually define how to handle them with a key function. But usually, it’s better to keep types consistent.

Sorting Nested Lists

Nested lists can also be sorted by values inside. Suppose you have:

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data = [[1, 9], [2, 3], [4, 1]]

data.sort(key=lambda x: x[1])

print(data)

# Output: [[4, 1], [2, 3], [1, 9]]

It sorts by the second number in each sublist. This can be helpful when sorting structured data like CSV rows or records.

Sorting Based on Computed Values

You can sort a list based on a calculated value from each item. This is useful when you want to sort based on some transformation, like the absolute value of numbers or a substring of each item.

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numbers = [-10, 3, -1, 7, -20]

numbers.sort(key=abs)

print(numbers)

# Output: [-1, 3, 7, -10, -20]

In this case, the list is sorted by absolute values instead of the original numbers. This is useful when you want to ignore the sign or sort based on a custom calculation. You can use any function in the key argument as long as it returns a value by which to sort.

Conclusion

Sorting lists in Python using sort() is one of the most useful and easy-to-learn tools in the language. Whether you're sorting numbers, strings, or objects, this method lets you do it quickly without extra setup. It works in place, gives you control of key functions, and can handle everything from case-insensitive sorting to arranging custom objects. The Python sort method is flexible and fast, making it ideal for everyday use in data cleaning, reporting, or just tidying up output. Once you get used to it, you'll find yourself reaching for sort() whenever you want to bring order to chaos in your code, projects, or daily data-related tasks.