Notice that a visitor's browser doesn't support Java script language

"Java" is a widely-used type of PC software provided by Sun Microsystems. This nonprofit, ad-free site uses Java scripts to launch informational popup windows to help you learn. It looks like your browser isn't Java-enabled or suppresses popups. Most browsers allow you to enable Java support and/or allow some or all popups.

To enable Java In the Internet Explorer browser, click "Tools," in the browser toolbar > "Internet Options," > "Secur-ity," and "Custom Level." Scroll down to "Java VM" and click the desired security level button. Then click "OK"

To regulate popups, click "Tools" > "popup blocker"

To download and install the latest free Java "Runtime Environ-ment" software, visit https://java.com and follow the directions.