---
title: "Glossary: analytics and example domain terms"
description: "Short explanations of _setDomainName, linker, _gl, cross-domain measurement, unwanted referrals, SearchAction, Change of Address and 410 Gone."
url: https://example-petstore.com/glossary
language: en
---

# Glossary

Short explanations of the terms used on this site, with links to the guides.

**Example domain**

A domain name used in documentation to stand for “your site”. Reserved example domains such as `example.com` lead nowhere; registered look-alikes such as example-petstore.com reach a real server. See [example domains](https://example-petstore.com/example-domains).

**Classic Analytics (`ga.js`)**

Google Analytics tracking code from 2007, using `_gaq.push()` and `pageTracker`. It no longer collects data. See [the Analytics guide](https://example-petstore.com/guides/google-analytics-cross-domain).

**Universal Analytics (`analytics.js`)**

The successor of Classic Analytics, using `ga('create', …)`. Standard Universal Analytics properties stopped processing data on 1 July 2023 (360 properties on 1 July 2024).

**Google Analytics 4**

The current version of Google Analytics, installed with the Google tag or Google Tag Manager. Cross-domain settings are made in the admin.

**Google tag (`gtag.js`)**

The script that sends data to Google Analytics 4 and other Google products. It is configured with `gtag('config', …)` and `gtag('set', …)`.

**Cross-domain measurement**

Counting one visit across several of your own domains, such as a shop and a checkout provider, as a single session.

**`_setDomainName`**

A Classic Analytics setting for the cookie domain. Google’s examples used `'example-petstore.com'`, `'.example-petstore.com'` or `'none'`. Google Analytics 4 sets the cookie domain automatically.

**`_link` and `_linkByPost`**

Classic Analytics functions that passed visitor cookies to another domain through a link or form. In the examples they pointed at dogs.example-petstore.com and example-commerce-host.com/petStoreCart.

**Linker and `_gl`**

The Google tag feature that adds a `_gl` parameter to links between your configured domains, so the visit continues on the other domain. Older code used `__utma` and similar parameters.

**Unwanted referrals**

A Google Analytics 4 list of referring domains, such as a payment provider. Analytics then ignores these domains as referrers (it adds `ignore_referrer=true`), so the visit keeps its original source, such as the ad or search that brought the customer.

**Self-referral**

Your own site showing up as the source of its traffic, usually because cross-domain measurement is missing or misconfigured.

**Structured data (JSON-LD)**

Machine-readable information about a page in a `<script type="application/ld+json">` block, using the schema.org vocabulary.

**`WebSite` markup**

A structured data block with your site’s `name` and `url`, placed on the home page. Google uses it when choosing the site name shown in results.

**`SearchAction` and the sitelinks search box**

Markup that asked Google to show a search box below a site’s result, sending searchers to the `target` address. Google stopped showing the box on 21 November 2024. See [the search box guide](https://example-petstore.com/guides/sitelinks-search-box).

**Change of Address tool**

A Search Console tool that tells Google a site has moved to a new domain. It requires both domains as verified properties and 301 redirects. See [the site move guide](https://example-petstore.com/guides/change-of-address).

**301 redirect**

A permanent redirect from an old address to a new one.

**Canonical URL**

The preferred address of a page, given with `<link rel="canonical">`. On this site, every address points to the home page as canonical.

**`hreflang`**

Annotations that link the language versions of a page, so search engines show the right one.

**Base URL**

The address an API client puts in front of every request path, such as `https://api.example.com/v2`. It belongs in configuration. See [the API guide](https://example-petstore.com/guides/api-base-url).

**`410 Gone`**

The HTTP status this domain returns to API requests: the resource is not available here and will not be.

**`application/problem+json`**

The standard format for HTTP API error details (RFC 9457), with `type`, `title`, `status` and `detail`.

**Credential rotation**

Revoking a key, token or password and issuing a new one. Required when a credential was sent to the wrong server. See [leaked credentials](https://example-petstore.com/guides/leaked-credentials).

## Related guides

### [The history of example-petstore.com](https://example-petstore.com/history)

When and where Google used example-petstore.com and example-commerce-host.com, from 2009 to today, with archived sources.

### [Example domains](https://example-petstore.com/example-domains)

Which names are reserved for documentation, why look-alikes like this one get real traffic, and what to use instead.

### [From Classic Analytics to Google Analytics 4](https://example-petstore.com/guides/google-analytics-cross-domain)

Remove `_setDomainName`, `_link` and `_linkByPost` code, install the Google tag, and set up cross-domain measurement and unwanted referrals the current way.