# Tracking Tag > The lightweight client-side script installed in a site's HTML head that opens sessions, assigns the Client ID, generates Click IDs, runs AutoTag/AutoTrack, and orchestrates connected ad pixels. The Tracking Tag is AnyTrack's client-side foundation: one lightweight script in the site's ``, present on every page of the funnel. It opens the session, assigns the Client ID, generates the Click ID on conversion events, captures UTM parameters as first-party data, runs AutoTag and AutoTrack, and orchestrates every connected ad pixel and integration. ## What the Tracking Tag does - **Assigns the Client ID** — the first-party cookie that anonymously identifies the visitor. - **Generates the Page Click ID (`atclid`)** on page load and a full Click ID for each trackable element. - **Captures attribution data** — UTM parameters and referrers, stored as first-party data. - **Runs AutoScan, AutoTrack, and AutoTag** to find trackable links/forms and append the Click ID automatically. - **Loads the ad-platform tags** (Meta Pixel, Google Tag) with the right identifiers, so you don't install them separately. ## How the Tracking Tag differs from similar terms - [Conversion API](/glossary/conversion-api) — the Tag runs client-side in the browser; the Conversion API delivers events server-side to ad platforms. - [Server-Side Tagging](/glossary/server-side-tagging) — the Tag fires to ad platforms client-side; server-side tagging does it from a server. The recommended setup runs both. - [Page Click ID](/glossary/page-click-id) — the Tag *generates* the `atclid`; it is not the identifier itself. ## How AnyTrack uses the Tracking Tag AnyTrack is the tag manager: the Tracking Tag loads the ad-platform pixels for you. Because privacy browsers and ad blockers can drop client-side JavaScript, purchase and lead conversions should also run server-side — that is why the Tag and server-side tagging are complementary, not alternatives.