Parameters are how you give details about how an applet should run. You use <PARAM ...> to communicate parameters. For example, if you want to tell MyApplet what text to display, you use the TEXT parameter.
The <PARAM ...> tag in the above example simply says TEXT="Hey Dude". This method of assigning a name with one attribute and a value with another is a way of bridging the gap between the worlds of HTML and Java.