Compiler design is the art and science of building software that translates code written in one language (source language) into another language (usually machine code) a computer can understand directly. It's like a skilled translator, taking your human-readable instructions and turning them into a language the machine can speak.

This involves analyzing the source code, breaking it down into smaller parts, checking for errors, and then generating the equivalent machine code instructions. Compiler design plays a crucial role in various fields, from programming languages to software development and even mobile apps.

Think of it as building a bridge between our ideas and the machine's capabilities.