Python Indentation: Why It Matters

Python is Indent-Sensitive

In most languages, indentation is just for humans. In Python, indentation defines code blocks. Get it wrong and your code doesn't run.

The Golden Rule

Use 4 spaces for each level. Be consistent.

if x > 0:
    print("positive")       # 4 spaces
    if x > 100:
        print("very large") # 8 spaces
    print("end inner if")   # 4 spaces
print("end outer if")       # 0 spaces

Tabs vs Spaces

Don't mix them. Python 3 actually forbids mixing. Pick spaces and stick with it.

Most editors (including PyForm and VS Code) insert 4 spaces when you press Tab.

Common Errors

Unexpected Indent

print("hello")
    print("world")  # ✗ shouldn't be indented

Expected an Indented Block

if x > 0:
print("positive")  # ✗ must indent

Inconsistent Indentation

if x > 0:
    print("positive")
  print("still here")  # ✗ 2 spaces doesn't match 4

Editor Tips

• Enable "show whitespace" to see tabs vs spaces
• Set editor to convert tabs to spaces automatically
• Use auto-indent features

In PyForm

PyForm's Monaco editor auto-indents when you press Enter after a colon, and uses 4 spaces by default. You'll rarely hit IndentationError.