What is 'code'?

Code is just text. Specifically, it's text written in a way the computer can follow as instructions. If you can write a recipe — do this, then this, then that — you can read code. Writing it well takes practice, but reading the basic shape of it is something you can pick up in an afternoon.

An example you can read right now

Here's a tiny piece of code in a language called Python. Read it out loud and see if you can figure out what it does:

name = "Harvey"
age = 30

if age >= 18:
    print(name + " is an adult")
else:
    print(name + " is a minor")

That's six lines of code and you can probably tell exactly what it does:

1. It says "remember the word Harvey and call it name."
2. It says "remember the number 30 and call it age."
3. It checks if age is 18 or more.
4. If yes, it prints "Harvey is an adult." If no, it prints "Harvey is a minor."

That's code. It uses some symbols you might not have seen (= means "assign," +means "join these"), but the logic is the kind of thing you already do every day.

What is a "language"?

That example was Python. Python is one programming language out of dozens that are commonly used. A language is just a set of rules for how to write code: what words it understands, what symbols mean what, how to organise your instructions.

Different languages exist because different jobs want different things:

• Python — easy to read; good for scripts, data, AI.
• JavaScript — runs in web browsers and on web servers; the language of the web.
• TypeScript — JavaScript with extra safety checks (this site is written in TypeScript).
• HTML— not really a programming language; it's a way to describe the structure of a web page.
• CSS — also not a programming language; describes how a web page looks.
• Bash — the language you type into a terminal to tell the computer to do things.

You will not have to learn any of these languages to start using Claude Code. But you'll see snippets in all of them, and the more you can read at a glance, the more useful Claude Code becomes — because you'll know if it's doing the right thing.

What does it mean to "run" code?

Code in a file is inert. Just text sitting on a disk. To actually do the thing the code describes, you have to run it. This means handing the file to a program that reads the code and executes each instruction.

For Python, that program is also called python. You type something like python my-script.py in the terminal, and the Python program reads my-script.py and starts following the instructions inside.

For JavaScript on a server, the program is usually node — you type node my-script.js. For JavaScript in a browser, the browser itself does the running, the moment the page loads.

What does "a bug" mean?

A bug is when the code does the wrong thing. Not because the computer broke — the computer did exactly what the code said. The bug is in the instructions. Either the person who wrote them missed a case, made a typo, or got the logic wrong.

Writing software is mostly fighting bugs. Even very good engineers write buggy code constantly; the difference is how fast they notice and how cleanly they fix it. Claude Code is excellent at this part — finding the dumb mistake in a thousand-line file and fixing it without you having to read the whole thing.