Hi there. In this lesson, we will introduce Java. In this section, we're going to learn about Java technology. First, we will learn what is the Java programming language, and then we'll be learning what is JDK, i.e., Java Development Kit, JRE, i.e., Java Runtime Environment, and JVM, i.e., Java Virtual Machine. Next, we will learn what Integrated Development Environment is. Then we will download and run Eclipse. Then we'll write the first Java program by using Eclipse. Then we'll be learning how to compile and run Java programs. Then we will review the first Java program. Let's look at what is Java and Java platform.

Java is a programming language and a computing platform for application development. It was first released by Sun Microsystems in 1995 and later required by Oracle Corporation. Now it is one of the most used and popular programming languages. Java platform is a collection of programs that help to develop and run programs written in the Java programming language. Java platform includes an execution engine, a compiler, and a set of libraries. 

Java is a platform-independent language. It's not specific to any processor or operating system. It's intended to let application developers Write once, run anywhere; meaning that compiled Java code can run on all platforms that support Java without the need for recompilation. For example, you can write and compile a Java program on UNIX and run it on Microsoft Windows, Macintosh, or UNIX machines without any modifications to the source code. Write once, run anywhere is achieved by compiling a Java program into an intermediate language called bytecode. The format of bytecode is platform-independent. 

In addition, the Java programming language is an object-oriented language. So, in Java everything is an object. Since it's based on the object model, Java can be easily extended. Java is designed to be easy to learn. If you understand the basic concept of object-oriented programming, it would be easy to master. We'll cover object-oriented programming concepts in the next lectures. So, what can Java technology do? The general purpose high-level Java programming language is a powerful software platform. Every full implementation of the Java platform gives you the following features: Development tools. 

The development tools provide everything you'll need for compiling, running, monitoring, debugging, and documenting your applications. As a new developer, the main tools you'll be using are the Java compiler, the Java launcher, and the Java doc documentation tool. Application Programming Interface, API. The API provides the core functionality of the Java programming language. It offers a wide array of useful classes ready for use in your own applications. 

It spans everything from basic objects to networking and security, to XML generation and database access, and more. The core API is very large. Deployment technologies. The JD care software provides standard mechanisms, such as the Java Web Start software and Java Plugin software for deploying your applications to end users. User Interface Toolkits. The JavaFX, Swing, and Java 2D Toolkits make it possible to create sophisticated Graphical User Interfaces (GUIs). Integration Libraries. Integration libraries such as the Java IDL API, JDBC API, Java Naming, and Directory Interface (JNDI) API, Java RMI, and Java Remote Method Invocation over Internet Inter-Orb Protocol Technology (Java RMI-IIOP Technology), enable database access and manipulation of remote objects. 

After this information about the Java programming language, let's look at what is JDK, JRE, and JVM. Java Development Kit (JDK) is a software development environment which is used to develop Java applications. This package includes all tools to develop with Java. If you want to develop and run the applications, you require to set up JDK on your machine, and the JDK contains the Java Runtime Environment (JRE) and Development Tools. The Development Tools are compilers, Java debugger, etc. 

Java Runtime Environment (JRE) is a software package which bundles the libraries and the Java Virtual Machine and other components to run applications written in Java. The JRE is the runtime portion of Java software, which is all you need to run it in your web browser. It contains Java Virtual Machine (JVM) and libraries. Java Virtual Machine is a virtual machine that runs Java programs. When you run the Java program, the Java compiler first compiles your Java code to bytecode. 

You get this bytecode by compiling the .java files into .class files. .class files contain the bytecodes understood by the JVM. Briefly, if you are a Java programmer, you will need JDK to develop and run the applications, and this package will include JRE and JVM as well. But if you are just a normal user who likes to play online games or run only programs written in Java, then you will only need JRE, and this package will not have JDK in it. Yes friends, I think you've learned what JDK is. Now we can install JDK on our computer. But let's take a short break here. In our next lesson, we'll install the JDK. See you in the next lesson.