Step 1: Up to this point, you've written code that runs in a person's browser, which is called client-side code. A client is a user with a browser. To have clients share information with each other, you can write server-side code. A server is a central computer that multiple clients can send requests to. To write server-side code, you can use Node.js, which is a JavaScript runtime that can run JavaScript code outside of a browser. Install Node.js by searching for it and downloading it from its website.