---
title: "How tracking works"
description: "What gets sent, and why it works when browser tracking usually does not."
slug: "en/customs/tracking/how-tracking-works"
url: "https://docs.custom.one/en/customs/tracking/how-tracking-works/"
capability: "tracking"
---
When someone moves through your custom, Custom One can tell your analytics and ad
platforms about it: that a page was seen, that a quiz was completed, that a
result was watched.

## Why this is worth setting up

Ad platforms optimise on what you report back to them. If Meta never learns which
clicks turned into completed quizzes, it can only optimise for clicks — so it
finds you people who click.

Once completions are reported, it can find you people who finish.

## Server-side, not just in the browser

Browser-based pixels lose a meaningful share of events to ad blockers, privacy
settings and browsers that block third-party scripts. Nothing is broken when that
happens, which is what makes it hard to notice: your numbers are simply lower
than reality, consistently.

Custom One sends events from its own servers as well. Those aren't affected by
what the visitor's browser allows, so the platform receives events it would
otherwise never see.

## What you need

One identifier per platform, copied from the platform itself. Each has a
recognisable shape, and Custom One checks it before saving:

| Platform | What you paste | Shape |
|---|---|---|
| Google Tag Manager | Container ID | `GTM-` followed by 6–8 characters |
| Meta Pixel | Pixel ID | 15 or 16 digits |
| TikTok Pixel | Pixel ID | a letter, then 15–30 letters and digits |

If the field rejects what you paste, you've almost certainly copied a different
ID from that platform — an account or ad-account ID rather than the container or
pixel.

## Setting one up

Each platform has its own page:

- [Set up Google Tag Manager](/en/customs/tracking/google-tag-manager/)
- [Set up Meta Pixel](/en/customs/tracking/meta-pixel/)
- [Set up TikTok Pixel](/en/customs/tracking/tiktok-pixel/)

You can connect all three at once. They don't interfere with each other.