Client Side Scripting
Server Side Scripting
The difference with Server Side Scripting is that when you trigger an event, your browser must send that information back to the server in order to know what to do next. For example when you fill out the design brief forms on this website, you are triggering php script. You enter your information and then hit submit. Your information is sent to the server where it's saved in a database. From there it gets formatted into an email and sent to me, so that I can read it.
Client-side scripting is useful because it uses your browser to load the program and can cut down substantially on load and reaction time because the browser doesn’t have to communicate with the server before taking action. The downfall with client-side scripting is that it can’t access any of the data that is stored on the server. For example, a website that sells shoes will have a database of their entire inventory on their server. In order to access the inventory, the programmer must use a server-side script.