1. Hello, World!

When you start to learn a programming language, the first program you write is typically one that prints Hello, world! to the terminal (or console). Below is the simplest Python statement that does exactly that.

print('Hello, world!')

Notice that this program is seemingly trivial, but a lot is going on. First, the print() command is actually a function. The word print is the name of the function, and the opening and closing parentheses indicate that we are calling (or invoking) a function. Inside the parentheses, we have a string literal, 'Hello, world!'. All string literals are enclosed by either a pair of single or double quotes. In this example, it is said that we are passing a string literal to the print function; the string literal is called a parameter of or argument to the print function.

That is already a fair amount of background for such a small program. Even so, it shows one of Python’s strengths early: simple tasks can often be expressed very directly. We have already touched on functions, arguments, and string literals while doing one of the simplest things possible in programming.

Note

When I specify string literals, do I use single or double quotes?

Single and double quotes may be used interchangeably to specify string literals in Python. When specifying string literals, be consistent; either always use single or double quotes, as best as you can, throughout your code.

1.1. Exercises

1.1.1. Print your name

Try printing your name to the terminal.

Solution

print('John Doe')
print('Jane Smith')

1.1.2. Print a complete sentence

Try printing a complete sentence to the terminal.

Solution

print('I am feeling fine today.')
print('Today is very cold.')
print('In fall, we fall back in time, in spring, we spring forward in time.')