# What is a computer program?

[Programming guides](README.md)

A computer program is a set of instructions that a computer can carry out. The instructions might calculate a score, draw a character, or ask a question. Writing those instructions is called **programming**.

You do not need to know everything before you start. You can write one instruction, run it, and see what happens.

## Be the robot

Ask a friend to pretend to be a robot. “Get ready for school” is too vague. “Pick up your bag” is more precise. A computer needs instructions that its programming language actually understands.

Order matters too. Putting your shoes on before your socks gives a different result from putting your socks on first. A simple Pliro program normally follows its statements from top to bottom. Loops, decisions, and events can change what happens next; you will meet those later.

## A tiny program

This program needs only a text output panel.

```pliro
# language: en
say "Pick up the bag."
say "Put the book in the bag."
say "Close the bag."
```

The first line chooses English syntax. Each `say` instruction displays some text. The quotation marks show where the text begins and ends; they are not part of the displayed message.

## Predict, then run

What is the second message? Does a real bag close?

```text
Pick up the bag.
Put the book in the bag.
Close the bag.
```

The program prints instructions. It does not move a bag: printing words about an action is different from performing that action. To draw, play sound, or control a device, a program needs the appropriate Pliro commands and a supporting host.

## Your challenge

Swap the second and third lines. Read the new order aloud before running it. Then write a three-line program that describes a robot dance.

## A common mistake

A computer cannot silently fix an unclear instruction by guessing your intention. A spelling mistake in a command may produce an error. That does not mean you are bad at programming: it means you have a specific clue to investigate.

## Where next?

[Algorithms](algorithms.md) · [Following a program](tracing.md) · [Displaying text](../builtins/say.md)