A class is like a blueprint, it contains different kinds of things such as variables,methods,constructors etc. Let's see how to declare a class. A class name should start from a capital letter. Ex: class HelloWorld{} Accessibility of variables can be changed according to Access Modifiers . There are four types of access modifiers. Private - visible only within the class. Protected - visible to any other class in the same package. Public - visible to any class. Default - same as protected. Visible to any other class in the same package. (-) mark is used to denote private variables. (+) mark is used to denote public variables. Ex: -name:String private String name; +mark:int public int mark;