what is singleton design pattern? how do you create a singleton code example

Example: what is singleton design pattern

Singleton Design Pattern is basically limiting our class so that 
whoever is using that class can only create 1 instance from that class.
       
I create a private constructor which limits access to the instance of the class.
Than I create a getter method where we specify how to create&use the instance.
    - I am using JAVA Encapsulation OOP concept.