What are the potential pitfalls of manually defining namespaces and autoloading mechanisms in PHP, and how can Composer help streamline this process?

Manually defining namespaces and autoloading mechanisms in PHP can be error-prone and time-consuming. Composer helps streamline this process by providing a standardized way to manage dependencies and autoload classes automatically.

// Composer autoloader
require 'vendor/autoload.php';

// Your PHP code goes here