# Core concepts: entry and output — Webpack

Source: https://www.geekswithgeeks.com/en/webpack/webpack-03

> Master entry points and output configuration.

## Entry and output explained

**Entry** tells Webpack where to start bundling. It can be a single file or multiple entry points. **Output** specifies where to write bundled files and their names. Output filename patterns use [name], [hash], [contenthash] for dynamic naming.

## Multiple entry points

Create separate bundles for different parts of your application.

```javascript
module.exports = {
  mode: 'production',
  entry: {
    app: './src/app.js',
    vendor: './src/vendor.js'
  },
  output: {
    filename: '[name]-[contenthash].js',
    path: __dirname + '/dist'
  }
};
```

Output:

```
Creates: app-a1b2c3d4.js, vendor-x9y8z7w6.js
```

## Use contenthash for cache busting

[contenthash] generates unique hashes based on file content. When content changes, the hash changes, forcing browsers to fetch the new version. [hash] changes on every build even if content is unchanged.

Quick check

**Quiz:** What does [contenthash] do in output filename?

- [x] Generates unique hash based on file content for cache busting.
- [ ] Compresses the file automatically.
- [ ] Adds metadata to the bundle.

*Answer:* Generates unique hash based on file content for cache busting.. Content hash ensures cache busting by changing the filename when content changes, forcing fresh downloads.