What Is Click ID (gclid, fbclid)?
Click IDs are unique identifiers that ad platforms automatically append to URLs when someone clicks an ad. Google Ads adds gclid (Google Click Identifier), Meta/Facebook adds fbclid, Microsoft Ads adds msclkid, and TikTok adds ttclid. Each click ID is unique to that specific click event and enables the ad platform to track what happens after the click: page views, conversions, and attribution.
Why Click ID (gclid, fbclid) Matters
Click IDs are the backbone of conversion tracking and attribution. Without them, ad platforms can't tell which clicks led to conversions, making it impossible to optimize campaigns. They're also increasingly important as third-party cookies phase out. Click IDs provide first-party, deterministic tracking that doesn't rely on cookies. For personalization, click IDs reveal which ad platform sent the visitor.
How Adaptly Relates to Click ID (gclid, fbclid)
Adaptly reads click IDs as one of several signals to identify a visitor's ad source. When a URL contains gclid, Adaptly knows the visitor came from Google Ads. When it contains fbclid, the visitor came from Facebook. Combined with UTM parameters, click IDs give Adaptly a complete picture of the visitor's ad context, enabling more precise and relevant personalization.
Click ID (gclid, fbclid) in Practice
A visitor clicks your Google Ad and arrives at yoursite.com/pricing?gclid=EAIaIQobChMI... Adaptly's script detects the gclid parameter, identifies this as Google Ads traffic, and checks for accompanying UTM parameters to understand the campaign and keyword context. Even if UTMs are missing, the presence of gclid alone tells Adaptly to personalize for paid search traffic with messaging appropriate for high-intent searchers.
Frequently Asked Questions
What is gclid?
gclid (Google Click Identifier) is a unique parameter that Google Ads automatically appends to your destination URLs when auto-tagging is enabled. It looks like ?gclid=EAIaIQobChMI... and is unique to each click. Google uses it to connect clicks to conversions in your Google Ads and Analytics accounts.
Should I use click IDs or UTM parameters?
Use both. Click IDs (gclid, fbclid) are automatically added by ad platforms and are essential for their native conversion tracking. UTM parameters are manually configured and provide human-readable campaign context for analytics tools. Adaptly reads both. Click IDs identify the platform, and UTMs provide campaign and keyword context.
Do click IDs work with iOS privacy restrictions?
Click IDs are first-party URL parameters, so they're not blocked by iOS App Tracking Transparency (ATT) or Safari's Intelligent Tracking Prevention (ITP). They pass through as part of the URL, not via cookies or third-party tracking. This makes them more reliable than cookie-based tracking in privacy-restricted environments.
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