JAR - Java Archive
A file format used to bundle multiple files into a single archive file. Typically a JAR file will contain the class files and auxiliary resources associated with applets and applications. However, a JAR file could contain libraries and extensions to the Java language itself, entire Java Applications, or Java utility code. By convention, JAR files end with a .jar extension.

Java
Sun's popular programming language. Java is a platform-independent (at least in theory), crash-protected, object-oriented language that can be used to write applets that run in a browser, servlets that run server-side, or independent programs. Java's syntax is similar to that of C++.

Java Applet
A program written in the JavaTM programming language that can be included in an HTML page, much in the same way an image is included. When you use a Java technology-enabled browser to view a page that contains an applet, the applet's code is transferred to your system and executed by the browser's Java Virtual Machine (JVM).

Java class files
The file or set of files that contain the code for a Java applet.

Java Servlet
Servlets are programs written in Java that run on a Web server and can produce dynamic pages. Also see JSP.

Java Virtual Machine (JVM, Java Runtime Environment)
A set of programs that allow for Java applets to be run on a particular computer system.

JavaScript
A simple client-side programming language created by Sun and Netscape. JavaScript can be embedded in HTML pages to create interactive effects and do tasks like validate form data. JavaScript is a separate language from Java. All popular modern browsers support JavaScript. A few hosts support server-side JavaScript.

JDBC - Java Database Connectivity
Java Database Connectivity, standardized DB interface for Java. This technology allows to write an application once, and use it with any SQL database that has a JDBC-driver.

jpg (.jpg)
Filename extensions of images in JPEG format.

JScript
Microsoft's implementation of ECMAScript standard based on JavaScript. Limited, object-based, interpreted scripting language. Here is the official JScript site. JScript is comparable to VBScript.

JSP - Java Server Pages
JSP allows web pages to be generated dynamically using a combination of XML tags and Java Servlets. JSP is an extension to Java Servlets allowing the dynamic generation of web pages.