Babel
In plain terms
A JavaScript compiler that converts modern code to widely-supported syntax.
Going deeper
Babel transpiles newer JavaScript (and JSX/TypeScript) into versions older browsers understand, enabling use of cutting-edge features today. It's a build-step staple.
Under the hood
Plugin/preset-based; handles JSX, polyfills, and proposed syntax, though native browser support and esbuild/SWC reduce its load.
Examples
JSX compilation, supporting old browsers, using new JS features, React builds.
Think of it like...
Like a translator turning modern slang into language everyone still understands.