Dear sir i wanted to know that if a web page will contane an applet and if client will call that web page then the byte code of applet will dounloaded loacaly and then execute. But here question is this that "Why applet is dounloaded localy and then execute why not remotely"
Because that's how applets work - they run inside of a browser. If you want to execute server-side Java code, use servlets. Of course, servlets can't show a Java GUI to a client, so each of those has their place.