start():

The start() method is called after init() . That is also called to restart an applet after it has been stopped. While init() is called once- the first time an applet is loaded - start() is called every time an applet's HTML document is shown onscreen. Then, if a user leaves a web page and comes back, an applet resumes execution at start ().'

paint():

The paint() method is called every time your applet's output must be redrawn. This condition can occur for various reasons. For instance , the window in that the applet is running   might be overwritten through another window and then uncovered. Or the applet window might be minimized and then restored. Paint()  is also called when the applet begins execution. Whenever the applet have to redraw its output whatever the cause, paint () is called. The paint() method has one parameter of type Graphics. This parameter will hold the graphics context that describes the graphics environment in that the applet is running. That context is used whenever output to the applet is required.