The Angular CLI is a command-line interface tool that helps developers create, build, and test Angular applications. One of the key features of the CLI is its ability to optimize the application bundle for production. This is done by using a technique called tree shaking, which removes any unused code from the bundle. This can significantly reduce the size of the bundle and improve the application's performance.

The Angular CLI also provides other optimization features such as code splitting, which allows the application to load only the necessary code for a particular page or feature. This can further improve the application's performance by reducing the initial load time. Additionally, the CLI provides a built-in production server that can be used to test the optimized bundle before deploying it to a production environment.

Using the Angular CLI to optimize the application bundle is useful because it can significantly improve the application's performance and reduce its load time. This is especially important for large applications that have a lot of code and dependencies. By removing any unused code and splitting the code into smaller chunks, the application can load faster and provide a better user experience. Additionally, using the CLI to optimize the bundle is a best practice because it is a standard way of optimizing Angular applications and is recommended by the Angular team.

// Install the Angular CLI globally
npm install -g @angular/cli

// Create a new Angular project
ng new my-app

// Build the application for production
ng build --prod