Server-side scripting is generally preferred to client-side scripting, so it should be used where possible. As server-side script tends to run away from the user frontend, it is less likely to affect loading times that a user would see as a poor user experience.
That said, it is still advisable to configure before customizing and avoid scripting at all, wherever possible. This is because script is harder to maintain and is more likely to cause issues between releases of ServiceNow.
Let's explore some common uses for server-side scripting and how to best achieve these tasks.