1. What is this?
A loop repeats a block. A for loop walks through a sequence: for i in range(5) runs with i = 0..4. range(1, 6) gives 1..5. Indentation (the spaces at the line start) marks which lines belong to the loop. A while loop repeats while a test stays true.
2. Why do we use it?
Processing rows, retrying, counting — loops turn one block into many executions.
3. Syntax breakdown
for i in range(1, 6):
Repeat with i = 1,2,3,4,5. The colon starts the block.
print(f"Step {i}")Indented line = inside the loop. Runs once per i.
print("Done")Not indented = after the loop. Runs once.
5. Common mistakes
- Forgetting the colon after for ...: — Python requires it.
- Inconsistent indentation — use 4 spaces per level, always.
- Thinking range(5) includes 5 — it stops at 4.
Practice task
Print the 3-times table: lines like "3 x 1 = 3" up to 3 x 5.
Hint
Use for i in range(1, 6): and print(f"3 x {i} = {3 * i}").
Try it below — tests run automatically when you press Run.
Output
Press Run to see output.
Mini quiz
3 questions. Answer, then check.
1. Which values does range(1, 6) give?
2. How does Python know which lines are in the loop?
3. What ends a for header line?