Dictionary
A collection of key-value pairs for looking up values by key.
A dictionary stores data as key/value pairs inside curly braces, like {'name': 'Sam'}. Instead of a numeric position you look things up by key. Keys must be unique, so assigning to an existing key overwrites its value, and .get() returns a fallback you choose when a key might be missing.
ages = {"Sam": 30, "Ada": 36}
print(ages["Ada"]) # look up a value by its key
ages["Lee"] = 25 # add a new pair
ages["Sam"] = 31 # reassign an existing key
print(ages.get("Max", 0)) # a default when the key is absent
Output
36 0
Where this shows up in real Python
Dictionaries map keys to values: counting how often things occur, holding configuration, or modelling JSON-like records you look up by name.
Commonly used Dictionary tools
dict is a built-in type with its own methods:
.get(key, default)— read safely instead of raising KeyError.keys() / .values()— view all keys or all values.items()— loop over key/value pairs together.setdefault(key, default)— read a key, inserting a default if missing.update(other)— merge another dict’s pairs in.pop(key, default)— remove a key and return its value
Official documentation: Python Tutorial: Dictionaries