Server-side tracking glossary: the terms explained
The words that come up when you set up server-side tracking, each in a few plain sentences, with a link to the article that goes deeper.
Ad blocker · Click ID · Client (server container) · CMP (consent management platform) · CNAME cloaking · Consent Mode · Conversions API (CAPI) · Cookie lifetime · Data layer · Deduplication · Enhanced conversions · Event ID · Event match quality (EMQ) · First-party cookie · gcs and gcd · Google tag (gtag.js) · Google Tag Manager (GTM) · IP cloaking · ITP (Intelligent Tracking Prevention) · Link tracking protection · Measurement ID · POAS (profit on ad spend) · ROAS (return on ad spend) · Same origin · Server container · Server-side tagging · server_container_url · Tagging server · Web container
Ad blocker
A browser extension or built-in browser feature that stops ads and, almost always, tracking too. It works from filter lists: lists of tracking domains such as google-analytics.com and of address patterns such as /g/collect. Google Analytics is blocked by default.
Click ID
A parameter an ad platform adds to the landing page address when someone clicks an ad, so a later conversion can be tied to that click: gclid, gbraid and wbraid for Google Ads, msclkid for Microsoft Ads, fbclid for Meta, ttclid for TikTok and li_fat_id for LinkedIn.
More: Recovering click IDs
Client (server container)
The part of a server container that picks up an incoming request and turns it into an event the tags can use. The GA4 client claims GA4 hits; the Google Tag Manager: Web Container client serves your web container through your tagging server.
CMP (consent management platform)
The tool behind your cookie banner, such as Cookiebot, CookieYes or Usercentrics. It asks visitors what they allow, remembers the answer and tells your tags, usually through Consent Mode.
CNAME cloaking
Pointing a subdomain of your website at another company's domain with a CNAME record, so their tracking looks like your own. Safari detects it and caps the cookies such a subdomain sets at 7 days.
Consent Mode
Google's way for tags to know what a visitor agreed to. Version 2 has four signals: analytics_storage, ad_storage, ad_user_data and ad_personalization. It is required for advertisers who use Google's ad products with visitors in the European Economic Area.
Conversions API (CAPI)
A server-to-server way to send conversions to an ad platform, next to or instead of its browser pixel: Meta's Conversions API, TikTok's Events API, and the Conversions APIs of LinkedIn, Microsoft, Pinterest and Snapchat. It needs an access token from the platform.
Cookie lifetime
How long a cookie lives before the browser deletes it. Whoever sets the cookie chooses a lifetime, and browsers cap it: Safari at 7 days for cookies set by JavaScript, Chrome at 400 days for any cookie.
Data layer
A JavaScript list on the page, window.dataLayer, that the site pushes events and details into, such as a purchase with its items. Google Tag Manager reads it to fire tags and fill in their values.
Deduplication
Counting an event once when it arrives twice, for example from a browser pixel and from a Conversions API. The ad platform recognises the pair because both copies carry the same event ID.
Enhanced conversions
A Google Ads feature that adds hashed customer data, such as an email address or phone number, to a conversion. Google matches it to signed-in users, so conversions are still measured when cookies are missing.
Event ID
A unique identifier for one event, sent with both its browser copy and its server copy, so the ad platform can deduplicate them.
Event match quality (EMQ)
Meta's score from 0 to 10 for how well the events you send can be matched to people on Meta. It rises with the customer details you send along, such as email address, phone number, IP address and the Meta cookies _fbp and _fbc.
First-party cookie
A cookie set for the domain of the website you are visiting. A third-party cookie belongs to another domain; Safari and Firefox block those by default. Server-side tagging on your own domain keeps marketing cookies first-party.
First-party tracking
Tracking whose requests and cookies belong to your own domain: the container loads from your subdomain, the hits go to your subdomain and the cookies are set for your domain. It is what server-side tagging on your own tagging subdomain gives you, and the reason blockers and browser limits bite less.
gcs and gcd
Two parameters on every Google hit that carry the visitor's consent state. gcs holds the analytics and ads storage state, for example G111 when both are granted and G100 when both are denied; gcd also says whether each signal was a default or the visitor's answer.
Google tag (gtag.js)
Google's tag for Google Analytics 4 and Google Ads, set up with a measurement ID (G-) or a conversion ID (AW-). In Google Tag Manager it is the Google tag; loaded outside Tag Manager it is the snippet called gtag.js.
More: Duplicate tracking
Google Tag Manager (GTM)
Google's tag management system. A container holds your tags, triggers and variables: a web container runs in the visitor's browser, a server container on a tagging server.
IP cloaking
Safari's name for a subdomain whose IP address is unrelated to the website's own, such as a tagging subdomain on another company's server. Since Safari 16.4, cookies set by such a subdomain are capped at 7 days, even when a server sets them.
ITP (Intelligent Tracking Prevention)
Safari's tracking protection. It blocks third-party cookies, caps cookies set by JavaScript at 7 days (24 hours after a click from a known tracking domain) and caps cookies from cloaked subdomains at 7 days too.
Link tracking protection
Browsers removing known click IDs from the addresses people open. Safari does it in Private Browsing and for links opened from Mail and Messages; Brave does it by default. The click can then no longer be tied to its ad.
More: Recovering click IDs
Measurement ID
The ID of a GA4 web data stream, in the form G-XXXXXXXXXX. The Google tag uses it to know which GA4 property the hits belong to.
POAS (profit on ad spend)
The profit your ads bring in, divided by what they cost. Bidding on POAS instead of ROAS lets the ad platform favour orders that earn the most, not the ones with the highest revenue.
More: Profit tracking
ROAS (return on ad spend)
The revenue your ads bring in, divided by what they cost. The usual target for automated bidding in Google Ads and Meta.
Same origin
Two addresses with the same scheme, host and port. Serving your tracking from a path on your own website, such as www.example.com/mb, makes it same-origin with your pages, so browsers treat it as part of your site.
More: Same-Origin Tracking
Server container
A Google Tag Manager container that runs on a server instead of in the browser. It receives the hits from your website, processes them with clients and tags, and forwards them to analytics and ad platforms.
Server-side tagging
A setup where the browser sends its tracking to your own tagging server, which forwards it to analytics and ad platforms, instead of every platform's script sending straight from the browser. It gives you control over what is sent, keeps cookies first-party and makes tracking harder to block.
Server-side tracking
The same setup as server-side tagging, named for the result rather than the tool: your tracking data is collected by your own server before it goes to analytics and advertising platforms. Both terms are used for the same thing; "tagging" comes from Google Tag Manager, "tracking" is the everyday word.
sGTM
Short for server-side Google Tag Manager: a Tag Manager container of the server type, which runs on a server instead of in the browser. The browser sends its hits to that server, where the container's clients and tags forward them to the platforms.
sGTM hosting
Running a server GTM container somewhere a browser can reach it, under your own subdomain. Managed sGTM hosting means the provider runs the server, the certificate and the updates; you keep the container and its configuration in Tag Manager.
More: sGTM hosting pricing
server_container_url
The Google tag setting that sends GA4 hits to your tagging server instead of straight to Google. Without it, the hits bypass your server container.
Tagging server
The server that runs your server container. Your website reaches it on a tagging subdomain, such as mbase.example.com, or on a path of your own website.
Web container
A Google Tag Manager container that runs in the visitor's browser. It holds your browser tags, such as the Google tag and ad pixels, and sends their hits to your tagging server.