This article is regarding UUID and where it is used. The UUID is generated using a cryptographically strong pseudo random number generator. It is belongs to the package java.util. It is used to generate random number which is stronger and there wont be any repetition of number. UUID can be used for Creating random file names, Maintaining different Session id in web application. Transaction id in Banking sector. Primary key in Database. public static void man(String[] args) { UUID uniqueId = UUID . randomUUID ( ) ; System . out . println ( "The unique id is" + uniqueId . toString ( ) ) ; }