Summary of Important Points

• A Java program is a set of interacting objects. This is the basic metaphor of object-oriented programming . The main principles of the object-oriented programming approach are:
  • Divide and Conquer : Successful problem solving involves breaking a complex problem into small, manageable tasks.
  • Encapsulation  and Modularity : Each task should be assigned to an object; the object's function will be to perform that task.
  • Public Interface : Each object should present a clear public interface that determines how other objects will use it.
  • Information Hiding : Each object should shield its users from unnecessary details of how it performs its task.
  • Generality : Objects should be designed to be as general as possible.
  • Extensibility : Objects should be designed so that their functionality can be extended to carry out more specialized tasks.

• Abstraction  is the ability to group a large quantity of information into a single chunk so it can be managed as a single entity. Abstraction is an overarching principle of the OOP approach.
• A computer  system generally consists of input/output devices, primary and secondary memory, and a central processing unit. A computer can only run programs in its own machine language, which is based on the binary code. Special programs known as compilers and interpreters  translate source code programs written in a high-level language, such as Java, into machine language object code programs.
• Application software  refers to programs designed to provide a particular task or service; systems software assists the user in using application software.
• The client/server  model is a form of distributed computing in which part of the software for a task is stored on a server and part on client computers.
• Hypertext Markup Language (HTML ) is the language used to encode WWW documents.