List vs Tuple vs Set vs Dictionary in Python

Four ways to store data

Python has four main built-in ways to store a collection of data: list, tuple, set and dictionary. They differ in whether they can change, whether they keep order, and whether they allow duplicates. Picking the right one makes your code cleaner and faster.

List

An ordered, changeable collection — the most common one.

fruits = ["apple", "mango", "banana"]
fruits.append("kiwi")     # add
fruits[0] = "orange"      # change
print(fruits)

Lists use square brackets [], keep their order, allow duplicates, and can be changed freely. Use them for data that grows or changes.

Tuple

An ordered collection that cannot be changed after creation.

point = (10, 20)
print(point[0])          # read is fine -> 10
# point[0] = 5           # ERROR: tuples are immutable

Tuples use round brackets (). They keep order and allow duplicates, but are fixed. Use them for data that should not change, like coordinates or settings.

Set

An unordered collection of only unique values.

nums = {1, 2, 2, 3, 3, 3}
print(nums)              # duplicates dropped
nums.add(4)
print(4 in nums)         # fast membership check

Sets use curly braces {} with just values. They drop duplicates automatically and are great for uniqueness and fast "is it in here?" checks — but they keep no order.

Dictionary

Stores key-value pairs, so you look up a value by its key.

student = {"name": "Aman", "marks": 88}
print(student["name"])    # Aman
student["class"] = 12     # add a pair
print(student)

Dictionaries use curly braces with key: value pairs. Use them when each value needs a meaningful label, like a record of fields.

Quick comparison

Common mistakes

• Trying to change a tuple. Tuples are immutable — use a list if you need to edit.
• Relying on set order. Sets have no order; do not expect items in sequence.
• Using a list when you need uniqueness. A set removes duplicates for free.
• Confusing set and dict braces. Both use {}; a dict has key: value, a set has only values.

Summary

• List [ ] — ordered, changeable, allows duplicates.
• Tuple ( ) — ordered, fixed (immutable).
• Set { } — unordered, unique values only.
• Dict { key: value } — labelled key-value pairs.
• Choose by whether you need to change data, keep order, or ensure uniqueness.

Next, dive into list comprehension, or loop over any of these with Python loops.