Hi Bala Java is programming language and it is open source. I think two or three tier is not related to Java because we can apply three or two tier in any programming language who has support OOPS and it's depands on your project requirement. If you want to know more about the Two and Three tier. You can see in following link which is posted on c-sharp corner website itself. http://www.c-sharpcorner.com/uploadfile/gowth/two-tier-and-three-tier-architecture-with-example/ We can use two and three tier as per our project requirement in Java.