Intro to Python — Your First Real Program
Install Python, meet the REPL, and write a program that takes input from a human and does something useful with it — all in one sitting.
Done Beginner Read
Written tutorials
Every lesson, in full.
14 deep tutorials · about 193 minutes of reading · runnable code, real gotchas, and a challenge at the end of each.
Nothing matches that yet. Try a different track or search term.
All tutorials
Python Basics — Lists, Dictionaries and Functions
The four data structures and the one language feature that every later lesson assumes you already know. This is the load-bearing lesson of the whole track.
Done Beginner ReadPython Loops and List Comprehension
For loops, while loops, enumerate, zip — and the comprehension syntax that replaces about eighty percent of the loops you were about to write.
Done Beginner ReadIntroduction to Regular Expressions in Python
Pattern matching without the fear. The dozen symbols that cover ninety percent of real use, plus groups, and the one function everyone reaches for first by mistake.
Done Beginner ReadHello World in PHP with XAMPP
Get a real web server running on your own machine, understand why you cannot just double-click a .php file, and serve your first dynamic page.
Done Beginner ReadBuilding a PHP Web Form
HTML forms, GET versus POST, superglobals, and the self-submitting page pattern that every PHP app is built on.
Done Beginner ReadBuilding a Factorial Calculator in PHP
Functions, loops and recursion applied to a problem small enough to hold in your head — plus the integer overflow that every factorial tutorial forgets to mention.
Done Beginner ReadInput Sanity Checks in PHP and JavaScript
Validate on the client for speed, validate on the server for safety — and understand exactly why skipping the second one gets you hacked.
Done Beginner ReadHow to Make a Beautiful Website with CSS
Take the working-but-ugly form from the last lesson and make it something you would actually show people — using custom properties, flexbox, grid and a real type scale.
Done Beginner ReadRuby For Loops and Iterators
Blocks, each, map, select, times and upto — and why an experienced Ruby developer will almost never write a for loop.
Done Beginner ReadBuild a Calculator App in Visual C#
A complete Windows Forms desktop app — drag the buttons, wire the events, and handle the state machine that every calculator tutorial gets subtly wrong.
Done Beginner ReadGetting Started with Racket
Install DrRacket, get past the parentheses in ten minutes, and learn the substitution model that makes functional code predictable.
Done Beginner ReadLeetCode 349: Intersection of Two Arrays
The set-versus-nested-loop lesson. Three solutions, from the one that gets you rejected to the one that gets you hired — and how to talk through each.
Done Easy ReadLeetCode 997: Find the Town Judge
A graph problem in disguise. Reframe trust as in-degree and out-degree and a fiddly problem collapses into ten lines and a single pass.
Done Easy Read