Java applets are a technology for running programs written in Java, a programming language, within a web browser. They were once common as a way to run sophisticated code on the World Wide Web, but as browsers have gotten more powerful, applets have fallen out of favor. Many modern browsers do not support Java applets.
Java Applet History
Java was once used within most web browsers. Browsers, starting with Netscape Navigator, which was popular in the 1990s, could run miniature programs known as Java applets within web pages. A rectangular section of a web page was fenced off for a Java applet to run.
These programs enabled sophisticated features beyond what could be coded using the web design language HTML, which was in its infancy. Flash, another programming tool, was also used for similar purposes.
Browsers That Support Java Applets
Many modern browsers do not support Java applets. Google Chrome, Apple Safari, and Mozilla Firefox have all dropped support for applets written in the programming language. The HTML code used to embed Java applets on a web page is deprecated, meaning it's no longer advisable to use it when writing new programs because it may not be supported.
If you need to use one of these browsers to run a Java applet, you may want to download an older version of the browser, since you can't easily enable Java in Chrome or Firefox if you're running a current version. Older versions of web browsers can have security flaws, so you may want to use a dedicated computer or virtual machine to run the older browser to avoid risks from malware and hackers.
Using Microsoft Internet Explorer
Microsoft Internet Explorer still supports Java, although you may need to enable support for Java if an applet does not load properly.
To do so, click or tap the "Tools" menu and select "Internet Options." From there, select "Security" and then choose "Custom Level." Within this menu, scroll down to "Scripting of Java Applets" and check the "Enable" button. Click "OK." If the applet you want to run doesn't immediately load after enabling Java, restart the browser.
Using Microsoft Edge
Note that Microsoft's new browser Edge does not support Java applets. However, you can ask Edge to open a particular website in Internet Explorer. To do so, click or tap the "More Actions" button in Edge and then select "Open with Internet Explorer." Make sure Java is enabled in Internet Explorer to view an applet.