Definition
Data Layer
A data layer is the shared event dictionary that makes data readable, sustainable, and standardized for systems such as GTM.
The layer that sends site events and user interactions to analytics tools in a consistent structure.
When each team names events differently, measurement quality decays over time. A data layer fixes this by creating one shared source of truth.
Defining events such as lead submit, form complete, or CTA click in one language makes reporting more trustworthy.