Once while interviewing for a technical analysis position, I was asked if I knew anything about Java. I knew something about Javascript, and I knew enough to know that Java was not the same thing. But that was it.

We front-end people (designers, content specialists, usability developers) hear about Java, .NET, etc., but rarely really understand how it all fits together.

What is Java?

Java is a programming language. (It is also an island in Indonesia, and an espresso drink I’m craving at this very moment.)

What does it do?

[Java] allows software designed and written just once for an idealized “virtual machine” to run on a variety of real computers, including Windows PCs, Macintoshes, and Unix computers. On the web, Java is quite popular on web servers, used “under the hood” by many of the largest interactive websites. Here it serves the same role that PHP, ASP or Perl might, although traditionally Java has been used for larger-scale projects.

WWW FAQs: What is Java?

Why is it cool?

Java applets allow interactive elements to be embedded within other applications, such as webpages displayed in a browser. And, in keeping with Java’s principle of portability,  “write once, run everywhere” means you’re not confined to only one browser.

OK, that’s not entirely true. You might need to download a Java plug-in, particularly if you’re running Internet Explorer, whose masters allowed their Java Standard Edition license with Sun Microsystems (now an Oracle Corporation subsidiary) to lapse.

There are pros and cons to Java. Some say programs and services written with Java run slower and require debugging to accommodate subtle differences in implementations. On the other hand: applets, people!