Both static classes and singletons are ways to achieve global sharing, but their implementation mechanisms and application scenarios are different.
A static class is a class that contains only static members and cannot be instantiated because all its members are static, so they will only exist in one copy in memory. Static classes are suitable for implementing some globally shared functions, such as logging, mathematical function libraries, common tool classes, etc. The advantage of static classes is that they are easy to use, methods and properties can be called without instantiation, and there is no need to consider issues such as thread safety.
The singleton pattern means that a class can only be instantiated once, and the instance can be accessed throughout the application. The singleton pattern is suitable for situations where some application state needs to be saved, such as configuration information, game progress, etc. The advantage of the singleton pattern is that it can access the members of the class through instantiation, avoiding some problems that may exist with static members, such as code maintainability and testability.
When implementing global sharing, both static classes and singleton patterns can play a similar role, but static classes are more suitable for implementing some general functions that do not require state maintenance, while singleton patterns are more suitable for saving application state. When using, you should choose which method to use according to your actual needs.