So far, every program we’ve written has behaved exactly the same way.

For example:

print("Hello!")

or

age = 25
print(age)

Every time we run these programs, they produce exactly the same output.

But most programs need to interact with the user.

In Python, that’s what the input() function is for.

Reading Input from the User

The simplest example looks like this:

name = input("What's your name? ")

When the program reaches this line, it pauses and waits for the user to type something.

For example:

What's your name? Anna

After the user presses Enter, the text they typed is stored in the variable name.

We can then use it later in the program.

print(name)

The output is:

Anna

Responding to the User

For example:

name = input("What's your name? ")

print("Hello,", name)

If the user enters:

Anton

the program prints:

Hello, Anton

Now the same program can produce different results depending on what the user types.

input() Always Returns a String

Let’s write another program.

age = input("How old are you? ")

print(age)

If the user enters:

25

the output is:

25

So far, everything looks fine.

But there’s an important detail.

To Python, this is not a number.

It’s a string.

Why Does That Matter?

Consider this example.

age = input("Age: ")

print(age + 1)

At first glance, it seems like the program should print the user’s age plus one.

Instead, it raises an error.

Why?

Because Python doesn’t allow you to add a string and a number together.

Converting a String to a Number

To convert text into an integer, we use the int() function.

age = int(input("Age: "))

Now the program works like this:

  1. It reads text from the user.
  2. It converts that text into an integer.
  3. It stores the result in the variable.

Now we can safely write:

print(age + 1)

If the user enters:

25

the output is:

26

What If the User Doesn’t Enter a Number?

What happens if the user types:

twenty-five

or

hello

Python won’t be able to convert that text into an integer.

Instead, the program will terminate with an error.

That’s perfectly fine for now.

A little later, we’ll learn how to handle situations like this gracefully.

What We Learned Today

Today we made our programs interactive.

  • print() displays information on the screen.
  • input() reads input from the user.
  • Everything entered through input() is initially a string.
  • To convert text into an integer, use the int() function.

Try It Yourself

Write a program that asks the user for their name and age.

Then print a message like this:

Hello, Anna!
Next year you'll be 26 years old.

Here’s a hint:

name = input("What's your name? ")
age = int(input("How old are you? "))

print("Hello,", name)
print("Next year you'll be", age + 1, "years old.")

Try experimenting.

  • Enter different names.
  • Change the age.
  • Intentionally type text instead of a number and see what happens.

Don’t be afraid of errors—they’re an important part of learning how programs work.

What’s Next?

Our programs can now receive input from the user.

But how can we make them behave differently depending on that input?

For example:

  • if the user is older than 18, print one message;
  • otherwise, print a different one.

That’s exactly what conditional statements are for, and we’ll explore them in the next article.