Dictionaries

Think about a real dictionary — each word has a definition. In Python, a dictionary works the same way: it stores data as key-value pairs, where each key maps to a value.

You’d use a dictionary when your data has labels. Instead of a list where you track things by position, a dictionary lets you look things up by name.

person = {
    "name": "Alice",
    "age": 30,
    "city": "New York"
}

Here, "name", "age", and "city" are keys. "Alice", 30, and "New York" are their values.

Creating a dictionary

Put key-value pairs inside curly braces {}. Separate each pair with a comma, and use a colon : between each key and value.

Keys must be unique — if you use the same key twice, the second value overwrites the first:

person = {
    "name": "Alice",
    "name": "Aly"   # overwrites "Alice"
}
print(person)  # Output: {'name': 'Aly'}

Values can be any type — strings, numbers, booleans, lists, even other dictionaries.

Try it out