Programming Basics
Generics in Programming
What generics are, the problem they solve, and how they look in Java, C#, TypeScript and Python — with constraints, wildcards and…
Programming Basics
The ideas every language shares. Start here if you have never written code before: what a program is, how variables and loops work, and how to think through a problem before you type anything.
16 guides
Programming Basics
Concurrency and Multithreading
The difference between concurrency and parallelism, when threads help and when they do not, and the two bugs — race conditions and…
Programming Basics
Functional Programming vs OOP
Objects bundle state with the code that changes it; functional programming keeps data and transformations apart and avoids changing anything. The same…
Programming Basics
Big O Notation Explained
Big O describes how the time a piece of code takes grows as its input grows. The six classes you will meet,…
Programming Basics
Functions and Functional Programming
What functions really are, what makes one pure, and the functional ideas — map, filter, reduce, immutability — that make everyday code…
Programming Basics
Advanced Data Structures
Beyond lists and dictionaries: stacks, queues, heaps, trees, graphs and sets, what each is genuinely good at, and when the extra complexity…
Programming Basics
Programming Languages Explained for Beginners
Why are there so many programming languages, and does the choice matter? A plain-English look at what languages have in common, how…
Programming Basics
What Is an Algorithm? Explained Without the Maths
An algorithm is just a clear set of steps for getting something done. Here is what that means in code, why some…
Programming Basics
Arrays and Lists Explained (With Simple Examples)
A list holds many values under one name, in order. Here is how to read, add, remove and loop over items —…
Programming Basics
Functions Explained for Beginners
A function is a named set of steps you can run whenever you need it. Here is how to write one, what…
Programming Basics
Loops Explained for Beginners
A loop repeats a block of code so you do not have to write it out ten times. Here is the difference…
Programming Basics
If Statements Explained for Beginners
An if statement lets your program choose between paths. Here is how conditions work, how to combine them, and why one equals…
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Where to go next
Python
Plain-English Python guides, from your first line of code to small programs that do real work.
56 guides
JavaScript
How JavaScript works in the browser, explained with short examples you can paste and run.
23 guides
Web Development
HTML, CSS and the pieces that turn code into a page people can visit.
10 guides
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