Java
The JavaScript is a computer language for developing client and server applications on the Internet. If a certain Web page has a Java application, it enables the Net user to perform a certain action (such as play an audio file or enter his/her credit card number). 

JPEG- Joint Photographic Experts Group
These experts developed a method for reducing the size of an image.  When you see an image file whose filename ends with "jpg", it means that it was compressed using the JPEG method. (See gif, filename extension.)

Jughead
A search engine for Gopher servers. Unlike Veronica, which searches  the entire Gopherspace, Jughead searches only the Gopher server it is located on.  Jughead performs a full-text search and doesn't search only titles (like Veronica does).
(See Gopher, search engine, Veronica.)