A coder is someone who writes instructions for computers using programming languages. When you play a video game, use an app on a tablet, or watch a video online, you're experiencing what coders created by writing thousands of lines of code.

Coders translate ideas into the precise step-by-step commands that computers need. If you wanted to make a simple drawing program, a coder would write instructions like “when the mouse button is pressed, draw a line following wherever the mouse moves” and “when the user clicks the color button, open a menu with color choices.” Computers can't understand vague instructions, so coders must think through every tiny detail and write it clearly in a programming language like Python, JavaScript, or Scratch.

The work requires patience, problem-solving skills, and creativity. Coders spend time debugging (fixing errors in their code), testing their programs, and figuring out better ways to make things work. A student learning to code might start with simple projects like making a character move around a screen, while professional coders build everything from weather apps to robots that explore Mars.

People sometimes use coder, programmer, and software developer interchangeably, though professional software developers often handle more complex projects. Anyone can learn to code, which is why many schools now teach basic coding skills alongside reading and math.