Use tuples when: Data shouldn't change (coordinates, RGB colors, database records)
You need dictionary keys or set elements with multiple values
You want to signal that data is read-only
Returning multiple values from functions Use lists when:
You need to add, remove, or modify elements
The collection will grow or shrink
Order matters and items might be rearranged When in doubt, ask: "Will this data change?" If no, consider a tuple. If yes, use a list.