It is a special class, for which we can not have more than one instance in system at a time. It provides a single global point of access to that instance. Hence it ensures that only one instance can be created for this class and every user is forced to use only that single instance for any operation.
- Any Utility Class: Generally utility classes do not have states with these and so a single instance of that class can serve the whole system.
- Memory Manager: An object which is responsible to manage the memory in system. Obviously only there should be only one instance of this object so that it can update the objects with the current memory availability and other objects can update its state for expected memory requirement.