Learn Core Java start from basics including important terms and concepts like Java Features, Class, Method & its signature, Object-Oriented Concepts, Java Virtual Machine, Java Dev. Kit, Java Runtime Env., Datatypes, Constructors, Modifiers, Variable Scopes, Difference in Overloading & Overriding, Object Oriented Concepts like Polymorphism & Encapsulation basics, Packages & its Types, Methods to Access Packages, Access Modifier, Interface, Inheritance,Multiple Inheritance, Final Class/Method/Variable, Abstract Class, Exception Handling, Custom Exception, Multithreading & its Life Cycle,Thread Creation by extending thread class & by implementing runnable class, Synchronization & its Types.