Behind the Follow Button: How Social Apps Handle Follows at Scale

A simple breakdown of what really happens when you tap Follow. Learn how systems store follow relationships, update feeds, send notifications, and scale to millions of users.

Imagine scrolling through your favorite app and finding someone interesting.

You tap the “Follow” button, expecting to see their updates from now on. It feels instant and simple.

But behind that click, there’s a complex architecture at work to make sure you get that content.

This blog breaks down what happens behind the “Follow” button. It explains how the system stores follow relationships, updates your feed, and notifies users at scale.

What Happens When You Click “Follow”?

Clicking the “Follow” button triggers the app to send a request to the server saying you want to follow a user. The server processes this request and creates a new follow relationship in the database.

On the front-end, the button might change to “Following” right away.

This is an optimistic UI update.

The app assumes the follow will succeed and updates the button without waiting.

If something goes wrong (network error or server issue), the app reverts the button back to “Follow” and shows an error.