Short note, 5 October 2026, 3 min read

Python has no braces: the whitespace is the code

Why four spaces decide what your program does, shown with one line that moves.

Most languages mark a block of code with curly braces. Python does not have them. It decides which lines belong to an if by how far they are indented, so moving a line sideways changes what the program does.

Five lines

age = 12
if age >= 18:
    print("adult")
    print("can vote")
print("done")

Line 2 asks: is age at least 18? Lines 3 and 4 are indented under the if, so they belong to it. Twelve is not at least eighteen, so both are skipped, and the program prints one line:

done

Move one line

Now delete four spaces from line 4. Nothing else changes.

age = 12
if age >= 18:
    print("adult")
print("can vote")
print("done")

That line has left the block. It no longer depends on the if, so it always runs:

can vote
done

A twelve-year-old can vote. The words in the file are identical; only the whitespace moved.

What to take from this

• The indentation is not decoration. It is how Python knows where a block starts and ends.
• A block ends at the first line that goes back to the left.
• Use four spaces per level, and never mix tabs and spaces in one file.
• If a line should depend on an if, a loop or a function, check that it is indented under it. This is the first thing to look at when a program runs the wrong lines.

What you see is what runs. That is the trade Python makes: no braces to match, and in return the layout has to be right.

New to Python? Start with Your first Python program.

This article goes with the video Python has no braces. Watch it on YouTube.