Vite is a Build Toolchain or a Development Orchestrator. While things like Deno and Bun are runtimes, Vite is a wrapper that coordinates several specialized tools to give you a cohesive experience.
Vite is a dev dependency that you install with a package manager of your choice. it's a Node.js script that tells another program to transform your code.
Vite uses:

• transpiler: esbuild (or swc)
• dev server: native esm
• dependency pre-bundler: esbuild
• production bundler: Rolldown / Rollup. (When you run npm run build, Vite switches tools entirely.)

Vite also attaches several "quality of life" tools that you would normally have to set up manually:

• HMR (Hot Module Replacement): A built-in engine that swaps edited code in the browser without a full page refresh.
• Asset Handling: It automatically handles CSS, images, and JSON. If you import a .png, Vite gives you the URL; if you import a .css file, Vite injects it into the page.
• PostCSS: It has built-in support for processing modern CSS.
• Environment Variables: It handles .env files automatically via import.meta.env.

Vite plugins

are code that hook directly into