In the above script it will change the display word from 'ccc' to 'Hello world'.
A server side runs its scripts before the HTML is loaded, not after as we can see today the range of server side languages is in use. In which PHP is one of most popular, as well as ASP.net and ruby on rails. They are called server side languages because their script are run not on your computer, but on the server.
In some cases, the client side is good and in some cases server side is good if we work on front-end scripting which is on client side for anything that requires user interaction such as a simple game and server side requires a dynamic data to be loaded user as a notice that tells the user they are logged in.
Client-side scripts rely on the user's computer. If that computer is slow they may run slowly while Server-side scripting tends to be used for allowing users to have individual accounts and providing data from databases.
Client side scripting is possible to be blocked by the user while Server side scripting cant be blocked by the user.
Response from a server-side script is slower as compared to a client-side script because the scripts are processed on the remote computer.
Client side scripting cant access the file system that resides at the web server while Server side scripting can access the file system residing at the web server.
In client side services are secure while server side there are security cosiderations when sending sensitive information.