What key problems does the Singleton pattern solve?

Singleton solves three key problems:

1. Limiting the number of instances. It guarantees that the class is created only once. This matters for objects where multiple instances would break the logic (for example, a logger, a cache, a settings dispatcher).
2. A global access point. It lets you get the same instance from anywhere in the program without passing it through parameters. This simplifies working with shared resources.
3. Controlling the object's lifecycle. The class manages its own creation and lifetime, eliminating duplication and unpredictability.

In this way, Singleton provides centralized, controlled, and unified access to a resource that must exist in the system as a single instance.