Content revised 21 October 2026.
A channel group organises traffic into categories using defined rules. Read the dimension’s scope and rules before comparing channel totals.
Identify the report scope
First-user and session acquisition answer different questions. A person’s first recorded source is not necessarily the source of the current session. Keep the chosen dimension visible in reports so a comparison does not mix them.
Check source and medium
A channel label is derived from available information and applicable rules. Review source, medium and campaign values when a visit appears unexpected. Not every non-search visit is Referral, and Direct can reflect missing source details.
Use custom groups deliberately
A custom channel group can help express a business reporting need. Document the conditions and their order, test representative records and keep the default group available for comparison. Renaming a group does not repair missing collection.
Maintain the definition
Google can update default classifications. Check current documentation rather than copying a fixed historical list forever. Explain changes in a report before treating a shifted category total as a change in customer behaviour.
Official guidance: Google default channel definitions.