Dictionaries organize data into **key-value pairs**, making them a powerful tool for efficient data retrieval.  

- You can use any **immutable** type as a dictionary key;
- **Tuples** can serve as keys, but only if they contain **strings, numbers, or other tuples**;
- A dictionary **cannot have duplicate keys** each key must be unique.  
- Dictionaries are enclosed within **curly brackets** `{}`.

If you want to store information about different countries, you can use country names as dictionary keys, with values stored as tuples.

# Create dictionary
countries_dict = {'USA': (9629091, 331002651), 'Canada': (9984670, 37742154), 
                  'Germany': (357114, 83783942)}

# Printing dictionary
print(countries_dict)

You access dictionary values using their **keys**. If the key is a string as in our example, make sure to enclose it in **quotation marks**. Similar to indexing lists or tuples, you place the key inside **square brackets** to fetch the corresponding value.

# Dictionary 
countries_dict = {'USA': (9629091, 331002651), 'Canada': (9984670, 37742154), 
                  'Germany': (357114, 83783942)}

# Information about Canada
print(countries_dict["Canada"])

Which of the following is NOT true about Python dictionaries?

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How can you retrieve a value from a dictionary by its key?

What is the difference between a tuple and a list?

How can you access the third element in this list?


What does the `copy()` method do for lists in Python?

Is there a strict limit on how deeply you can nest tuples/lists/dictionaries in Python?

How do you update a value in a dictionary?

How would you change "green" to "yellow"?

Python Dictionaries