Can you explain what is meant by the Singleton pattern in programming?

The Singleton pattern guarantees that a class has only one instance and provides a global point of access to it.

Main characteristics:

• The class constructor is private or protected to prevent instantiation from outside.
• The class contains a static method that returns the single instance.
• The instance is created either lazily upon first request or immediately.

Example in C++:

class Singleton {
private:
    Singleton() {} // private constructor
    Singleton(const Singleton&) = delete;
    Singleton& operator=(const Singleton&) = delete;

public:
    static Singleton& getInstance() {
        static Singleton instance; // created once
        return instance;
    }

    void doSomething() {
        // ...
    }
};

// Usage:
Singleton& s = Singleton::getInstance();
s.doSomething();

This pattern is useful when a single shared object is needed, for example, for managing configuration or resource access.