7 Mind-Blowing Uses of Underscore in Python (That Most Devs Ignore)

It’s just an underscore… until you realize it’s doing way more than you thought.

7 Mind-Blowing Uses of Underscore in Python (That Most Devs Ignore)

When you first start coding in Python, underscores seem like mere stylistic choices — maybe a way to name variables or functions. But dig deeper, and you’ll discover that this seemingly humble character (_) is doing a lot more heavy lifting behind the scenes than most developers realize.

From serving as a placeholder to signaling intent to future readers of your code (including your future self), the underscore is one of Python’s most subtly powerful tools. Let’s uncover seven underrated, mind-blowing uses of the underscore that can level up your Python game.

1. Single Underscore _ as a Throwaway Variable

Ever need to loop through something just for its side effects and don’t care about the actual value? Enter the underscore.

for _ in range(5): 
    print("Hello, world!")

Here, _ indicates that the loop variable is intentionally unused. It's a subtle signal to readers: “Hey, I don’t care about this value.” Python doesn’t enforce this, but it’s a clean, readable convention that shows you're being intentional.

2. Single Underscore in the Interpreter

When you’re working in the Python REPL or interactive shell, _ holds the result of the last executed expression. It’s like a built-in memory buffer.

>>> 10 + 20 
30 
>>> _ * 2 
60

Super handy for quick calculations, experiments, or just being lazy in a good way.

3. Single Leading Underscore _var for “Internal Use” Variables

You’ve probably seen variables prefixed with an underscore in libraries or frameworks:

class MyClass: 
    def __init__(self): 
        self._internal_value = 42

This tells other developers: “This is for internal use. Hands off.” It doesn’t enforce strict privacy (Python doesn’t really have private variables), but it’s a respected convention — and tools like linters recognize it.

4. Double Leading Underscore __var for Name Mangling

This one gets spicy.

class MyClass: 
    def __init__(self): 
        self.__secret = "hidden" 
 
obj = MyClass() 
print(obj.__secret)  # AttributeError

Why? Python performs name mangling to protect this variable from being accidentally overridden in subclasses. It renames __secret to _MyClass__secret behind the scenes.

print(obj._MyClass__secret)  # Works

Use this only when you really want to avoid name clashes in inheritance chains.

5. Double Leading and Trailing Underscore __init__ — Dunder Methods

No Python article is complete without mentioning “dunders” (double underscores). These are special methods with specific meaning, like:

• __init__: constructor
• __str__: string representation
• __len__: length of object

class Book: 
    def __init__(self, title): 
        self.title = title 
 
    def __str__(self): 
        return f"Book: {self.title}" 
 
print(str(Book("1984")))

Rule of thumb: don’t invent your own dunder methods unless you’re creating new behavior for Python’s internals.

6. Underscore in Numeric Literals

Python 3.6+ lets you add underscores to numbers for better readability.

population = 1_400_000_000 
price = 49_999.99

It’s still just an int or float under the hood, but now your code is way more readable. Pro tip: Great for working with financial data, large IDs, or memory sizes.

7. Underscore in Pattern Matching (Python 3.10+)

If you’re using Python 3.10 or newer, you’re in for a treat with structural pattern matching.

def handle_point(point): 
    match point: 
        case (0, 0): 
            print("Origin") 
        case (_, 0): 
            print("X-axis") 
        case (0, _): 
            print("Y-axis") 
        case (_, _): 
            print("Somewhere else")

The _ acts as a wildcard pattern—matching anything without binding the value. Think of it like default: in a switch statement but even cleaner.

Final Thoughts

The underscore in Python is more than just a naming convention — it’s a quiet operator, a coding best practice, and a language feature all rolled into one.

The more Python you write, the more you’ll appreciate these little touches of elegance baked into the language. Start paying attention to where and how you (and others) use underscores. It might just help you write cleaner, smarter, and more Pythonic code.

Have a cool use of underscore you’ve seen or used? Share it in the comments — let’s underscore the underscore together.

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