Two things every single program eventually needs to do: make a choice, and repeat something. Python handles both with less punctuation than most languages, which is either delightful or slightly unsettling the first time you see it, depending on where you're coming from.

if, elif, else

age = 20
if age < 13:
    print("Child")
elif age < 20:
    print("Teenager")
else:
    print("Adult")

Notice there's no "else if" — Python uses elif, one word, no space. Also notice the colon at the end of each condition, and the indentation underneath it. That indentation isn't decoration, it's literally what tells Python which lines belong to which branch. Four spaces is the convention almost everyone follows, and honestly, just let your editor handle it rather than counting spaces by hand.

The for loop

for i in range(5):
    print(i)

This prints 0 through 4. range(5) generates five numbers starting from zero, which trips up basically every beginner at least once — you ask for range(5) expecting 1 through 5, and Python hands you 0 through 4 instead. Once you know it's coming, it stops being surprising.

Looping over real things, not just numbers

colors = ["red", "green", "blue"]
for color in colors:
    print(color)

This is honestly the loop you'll write most often in Python. Rather than looping over a range of numbers and then indexing into a list, you just loop directly over the list itself. It reads closer to plain English, and that's very much the point.

The while loop

count = 0
while count < 3:
    print(count)
    count += 1

Use while when you genuinely don't know ahead of time how many times you'll repeat something, waiting for a condition to change rather than counting through a fixed range.

break and continue

break jumps out of a loop entirely, and continue skips straight to the next round without finishing the current one. Both are handy, but if you find yourself reaching for them constantly, it's often a sign the loop's condition could be written more clearly in the first place. Not always — sometimes they really are the right tool — but worth a second thought.

One thing to watch for

Because indentation is meaningful, mixing tabs and spaces in the same file can cause errors that are maddening to track down, since two lines can look identical on screen but be indented differently underneath. Pick one — spaces are the near-universal convention in Python — and stick with it.