Introduction to Python

What is Python?

Python is one of the world's most popular programming languages. It was created by Guido van Rossum in 1991 and is known for being easy to read and write. Python is used for web development, data science, artificial intelligence, game design, and much more.

Unlike some other languages, Python reads almost like English, which makes it a fantastic first programming language. Let's start with the most famous program in all of coding:

# This is your first Python program!
print("Hello, World!")

When you run this program, Python will display the text Hello, World! on the screen. The print() function tells Python to output whatever is inside the parentheses.

Running Python Code and Writing Comments

You can run Python code using an online editor (like Replit or Trinket), or by installing Python on your computer and running files from the terminal. Python files end with the .py extension.

Comments are notes you leave in your code for yourself or other programmers. Python ignores comments when running your program. You write a comment using the # symbol.

# This is a comment - Python will skip this line
print("This line will run")  # You can also comment at the end

# Comments help explain what your code does
# They make your code easier to understand

Good programmers write comments to explain why they wrote something, not just what the code does. This is especially helpful when you come back to your code weeks later.

The print() Function

The print() function is your main tool for displaying output. You can print text (strings), numbers, and even calculations.

# Printing text (strings)
print("My name is Alex")
print('You can use single quotes too')

# Printing numbers
print(42)
print(3.14)

# Printing calculations
print(10 + 5)      # Output: 15
print(100 - 37)    # Output: 63

# Printing multiple items
print("I am", 14, "years old")

Notice that when you print multiple items separated by commas, Python automatically adds spaces between them. The last line above would output: I am 14 years old.

Key Vocabulary

Worked Examples

# Printing personal info on separate lines
print("Name: Alex")
print("Age: 14")

# Calculate 25 times 4
print("25 x 4 =", 25 * 4)

# Display a greeting message to the user
print("Welcome to BrightPath!")
# Note: The original had Print() with a capital P
# Python is case-sensitive, so it must be print()

Knowledge Check

Select the correct answer for each question. Click "Check Answer" to see if you are right.