Client-side

Client-side refers to programming code that runs on the client's side, rather than on the server's side (server-side). JavaScript is a client-side programming language.

Importantly, a client-side application, such as that created in JavaScript, can be accessed at the source level by the client, allowing website visitors, if they should wish, to view the code used to create an application. This also means that the client can copy this code, or block this code, preventing it from executing.

For example, a website attempting to protect it's content may use a short piece of JavaScript to prevent users being able to access the right-click menu. A visitor would then be able to block this script from executing, allowing them to freely right click.