Here's your decision guide: Use a list when: - Order matters. You need to modify, add, or remove elements. Duplicates are allowed. You need index access Use a tuple when: - Data shouldn't change.
You need a dictionary key with multiple values. Returning multiple values from functions Use a set when: - You need unique elements only. Fast membership testing matters.
You need union/intersection operations. Order doesn't matter Use a dictionary when: - You need key-value pairs. Fast lookup by key Choosing right makes hard problems easy. Choosing wrong makes easy problems hard.