Python Fundamentals

Python is a high-level, general-purpose programming language known for clean, readable syntax that looks close to plain English. It is beginner-friendly -- you write working code with very little boilerplate -- yet powerful enough for web development, data analysis, automation, and AI. Python is interpreted, so your code runs line by line with no separate compile step and you see results immediately. In this course you start here, then build up through variables, control flow, functions, and small projects.

Download Python from python.org and run the installer -- on Windows, tick "Add Python to PATH" so you can run it from any terminal. Check it worked by opening a terminal and typing python --version. Then install an IDE (the editor for your code): VS Code, PyCharm, or Thonny for absolute beginners. An IDE gives you syntax highlighting, error hints, and a run button. The "Installing Python & IDEs" lesson walks through every step.

A variable is a name that stores a value, created by assignment -- for example age = 25 or name = "Sara". Python figures out the type for you. Naming rules: a name must start with a letter or underscore; can contain letters, digits, and underscores; is case-sensitive (age is not the same as Age); and cannot be a reserved keyword like if or for. By convention, use lowercase with underscores, like first_name, and pick descriptive names. The two "Variables and naming rules" lessons cover this in detail.

print() displays output -- print("Hello") shows Hello on the screen. input() pauses the program, waits for the user to type, then returns what they typed as text -- for example name = input("Your name: "). Because input() always gives back a string, to do math you must convert it first, for example age = int(input("Age: ")). Together these two let your program talk to the user. See the "Basic input/output" lesson.

Operators are symbols that act on values. The main groups are: arithmetic operators (plus, minus, multiply, divide, floor-division, modulo, power) for math; comparison operators (equal, not-equal, greater-than, less-than) which return True or False; logical operators (and, or, not) for combining conditions; and assignment operators for storing results. For example, 10 floor-divided by 3 gives 3, and 2 to the power of 3 gives 8. The "operators" lesson covers each group with examples.

Conditional statements let your program make decisions. Use if to run code when a condition is True, elif to check another condition, and else for everything else. The condition is any expression that evaluates to True or False. Indentation matters -- the indented block belongs to the if. The "Conditional statements" lesson covers this, and "Nested conditions" goes further with conditions placed inside other conditions.

Loops repeat a block of code so you do not have to write it many times. A for loop runs once per item in a sequence -- for example, looping over a range of five numbers repeats five times. A while loop runs as long as a condition stays True. Use loops to process every item in a list, repeat until the user quits, or count through numbers. The break statement exits a loop early; continue skips to the next round. See the "Loops" lesson.