Javascript

Is the most popular scripting language used for

- Detects visitors browsers

- Form validation

- Add interactivity

-Set cookies

but most important i liked about jscript is it reduces server load.

To deal with those browsers who does not support javascript, write your jscript code in <-- tags//--> or use noscript tags.

When you want to call function from external jscript then first include that script file write another script tag in this tag you can call that function. You cant call function in first script tag.