Python, from zero.

What is Python?

Python is a high-level programming language, which means it reads much closer to plain English than to the raw instructions a computer executes. That readability is a big part of why it's often a first language.

It's also general-purpose. The same language builds web applications, cleans and reshapes data, and trains machine learning models — you're not learning a niche tool, you're learning something used across most corners of software.

Naming conventions

Python doesn't force much on you, but variable names follow a few habits worth learning early.

• lowercase Keep variable names in lower case — name, total_score — rather than Name or NAME.
• start char A name has to start with a letter or an underscore, like age or _temp.
• numbers Digits are fine inside a name — number1 — but a name can't start with one.
• case-sensitive firstName and firstname are two different variables to Python, even though a person might read them as the same word.

Indentation instead of brackets

Most languages mark where a block of code begins and ends with braces. Python uses whitespace instead — the indentation itself is the structure, not just a style choice.

function myFunction() {
  // code lives inside the braces
  // ...
}

def my_function():
    # code lives inside the indent
    # ...

Variables

A variable is a container for a value you want to store and use later. Unlike languages that ask you to declare a type up front — this holds an integer, that holds text — Python figures the type out on its own, from whatever value you assign.

Example assignment

x = 5            # x is an integer
name = "John"     # name is a string
price = 99.99     # price is a float
is_active = True  # is_active is a boolean

The = symbol

It's worth slowing down on this one, because it doesn't mean what it means in a math class. When you write:

name = "John"

The = sign is an instruction, not a comparison — it takes whatever is on the right and puts it into the box named on the left.

Data types

The four you'll meet constantly as a beginner:

Output — print()

Before a program can ask you anything, it needs a way to talk back. That's what print() is for — it lets your program display information to the user.

The simplest version

print("Hello World!")

Printing a variable

name = "Jordan"

print(name)

Printing text and a variable together

age = 15

print("My age is", age)

Separate them with a comma and print() handles the spacing for you.

name = "Your Name"
age = 15
favorite_color = "Blue"

Input — input()

Output goes one way: program to person. input() is what lets a person talk back.

name = input("What is your name? ")

print("Hello", name)

The process

• USER
• ↓
• INPUT
• ↓
• VARIABLE
• ↓
• PROCESSING
• ↓
• OUTPUT

So what actually happens when this line runs?

name = input("What is your name? ")

The computer, in order:

1. Displays the question
2. Waits for the user
3. Receives the answer
4. Stores the answer in name

Mini project — About Me

A first small program, built from everything so far: variables, input, and output.

Example

name = input("What is your name? ")
age = input("How old are you? ")
food = input("What is your favorite food? ")
game = input("What is your favorite game? ")

print("My name is " + name)
print("I am " + age + " years old")
print("My favorite food is " + food)
print("My favorite game is " + game)

A program to write on your own, using everything covered on this page so far.

Example output

===== GAMER PROFILE =====

Name: Alex
Age: 15
Favorite Game: Minecraft
Platform: PC

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