The for Loop in Python

The while loop is great when you don't know in advance how many times you'll repeat — you just keep going until some condition changes. But very often, you already know exactly what you want to repeat over — like "every number from 1 to 10" or "every letter in this word." For that, Python gives you something more direct: the for loop.

for i in range(1, 6):
    print(i)

# Output:
# 1
# 2
# 3
# 4
# 5

What you will learn

• How a for loop pulls values one at a time from a sequence
• Why range(1, 6) stops before 6, not at 6
• Looping over strings and lists directly
• How to control start, stop, and step with range()
• When to reach for for instead of while

Breaking down for i in range(1, 6):

• range(1, 6) — creates a sequence of numbers starting at 1, and stopping before 6. So you get 1, 2, 3, 4, 5 — five numbers, not six. This "stop before, not at" behavior catches almost every beginner at least once, so keep an eye on it.
• for i in ... — this means: one at a time, take each value out of that sequence, call it i for this trip through the loop, and run the body.
• The loop automatically runs once for every single item in the sequence, and then stops on its own — no break, no condition to write yourself, no risk of an infinite loop by accident.

Looping over strings and lists

You can also loop over the actual characters in a piece of text:

word = "cat"
for letter in word:
    print(letter)

# Output:
# c
# a
# t

Or loop over items inside a list:

fruits = ["apple", "banana", "mango"]
for fruit in fruits:
    print(fruit)

# Output:
# apple
# banana
# mango

range() with a start, stop, and step

range() actually accepts up to three numbers — a start, a stop, and a step:

for i in range(0, 10, 2):
    print(i)

# Output:
# 0
# 2
# 4
# 6
# 8

The third number (2 here) is the step — how much to jump by on each repeat. If you leave it out, Python assumes a step of 1, like in the very first example. You can even count backwards using a negative step:

for i in range(5, 0, -1):
    print(i)

# Output:
# 5
# 4
# 3
# 2
# 1

This is actually a cleaner way to write the countdown function from the while loop article — no manual decrement needed.

Common mistakes

• Expecting range(1, 6) to include 6 — it stops before the stop value
• Reaching for while with a manual counter when a plain for i in range(...) would be shorter and safer
• Forgetting that a negative step is required to count downward with range()
• Trying to modify a list while looping over it directly with for — this can skip items unpredictably