What is a singleton in programming?

A Singleton is a design pattern used in software development to ensure that a class has only one instance throughout the application's lifecycle. This pattern provides a global point of access to that instance, which can be useful for managing shared resources like configuration settings or database connections. Singletons are commonly used in object-oriented programming languages and help to prevent the creation of multiple objects that could lead to inconsistent behavior. However, they should be used carefully, as improper use can lead to issues with testing and increased coupling.