A class is a blueprint through which an object is created.

logical representation of data is called "class".syntactically class is also keyword,which represents class.blueprint,logical data view example:public class Animal{ Dog,Cat,...} physical representation of data is called "Object". example: physical existence of data is called "object". mean Dog d1=new Dog(); similarities between object and class. object mean like physical building already constructed. class mean like civil engineer created building plan image,blueprint on paper without physical existence. other: java.lang.Object is super class of all java Classes. for every java class internally ,builtin default Thread is 'main' METHOD.public static void main(String args[]){}. for every java class default implicit,internal import package is import java.lang.*; mean no need to import.it will automatically imported defaultly.