New Python developers usually treat type hints as optional decoration — something you add later, if at all. I'd argue they're one of the highest-leverage habits you can build early.
The obvious benefit is editor support: autocomplete gets sharper, and typos in attribute names get caught before you run anything. But the deeper benefit is what happens while you're writing the hint in the first place.
Writing `def get_user(user_id: int) -> User | None:` forces a decision you might otherwise skip: what happens when the user doesn't exist? Do you return None, raise an exception, or return an empty object? The type signature makes that contract explicit instead of implicit.
Tools like mypy or pyright turn those hints into an actual safety net, catching a category of bugs — passing the wrong shape of data — before your tests even run.
Start small. You don't need to annotate every internal variable. Annotate function signatures first, since that's where the contract with the rest of your codebase actually lives.
Written by Priya
Priya spent five years as a backend engineer building Python services before becoming a full-time AI trainer. She's onboarded dozens of junior developers.
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