Explain the differences between Server-side and Client-side code

Server side validation can be done on server side controls
using server controls.
But Client side validation can be done at browser.

The control validation can be done at client browser instead
of server side validation.Because its additional overhead to
the server.

For example,Mandatatory fields checking.It can be done at
client browser.No need at server side.

But the login and password must be validate at server side.

The client side validation can be done using the Javascript
or vb script.