Server side code excuted in server
Client side code excuted on clients browser.

Server side code is executed on the server, so it will be executed when page is posted back to the server. Client side code is executed on the client's machine for which we use scripting. Client side code is much faster than server side code.

Server side code is takes a request from client,and it replies to client,means serer side code is like back end,and client side code is front end

for example u can use client side scripting languages like javascript and vbscript for form validations like, user name should not be blank, password must contain this no. of characters like that...which executes in client's browser, whereas server side scripting languages aka code-behind files executes in the server, processes the client's request and sends back the processed output to the client as HTML page...