In what situations is it advisable to use the Singleton pattern?

The Singleton pattern is used when it is necessary to guarantee the existence of only one instance of a class in an application and to provide a global access point to this instance. Typical situations:

• Managing application configuration, where all components should use the same settings.
• Logging, so that all messages go through a single logger object.
• Working with database connections to avoid creating multiple connections.

Example in PHP:

class Singleton {
    private static $instance = null;

    private function __construct() {}
    private function __clone() {}

    public static function getInstance() {
        if (self::$instance === null) {
            self::$instance = new self();
        }
        return self::$instance;
    }
}

// Usage
$instance = Singleton::getInstance();

It is important to remember that Singleton can complicate testing and violate OOP principles, so it should only be used when a single instance is truly needed.