Dictionaries in Python

Dictionaries are one of the most useful and flexible data structures in Python. They store data as key-value pairs – like a real dictionary where you look up a word (key) to find its definition (value).

Dictionaries are mutable, unordered (order is preserved from Python 3.7+), and keys must be unique and immutable (strings, numbers, tuples).

They’re perfect for representing real-world objects: a person with name/age, a product with price/stock, or settings with options.

Creating a Dictionary

Use curly braces {} with key: value pairs separated by commas.

Accessing Values

Use square brackets with the key, or .get() method (safer – returns None if key missing).

Adding and Updating Items

Just assign a value to a key – creates if missing, updates if exists.

Removing Items

Use del, pop(), or clear().

Looping Through Dictionaries

Loop over keys (default), values, or items.

Nested Dictionaries

Dictionaries can contain other dictionaries – great for complex data.

Quick Quiz