J

Java – a programming language from Sun Microsystems that was designed for writing programs (Applets) that include animations, scrolling text, sound effects, games, etc. that can be downloaded from the Web without fear of viruses or other harm to your computer.

JavaScript – a scripting language widely used to create pop-up and pop-under ads, and other functionality, on web pages.

JPEGs – Joint Photographics Experts Group is a compression technique for colour images and photographs and, therefore, how they are saved. There is a future possibility that JPEG viruses might emerge; these are best resisted by doing the basics consistently.

Junk mail – unsolicited commercial bulk e-mail. Some junk mail is useful, and some of the mail that finds its way into your junk mailbox is mail that you specifically asked to receive.