Channels: Direct, Organic Search, Organic Social, Organic Video, Paid Search, Paid Social, Paid Other, Email, Display, Affiliates and Referral. AI assistants such as ChatGPT and Gemini count as referral sources
Sources: the referring site or app
UTM campaigns: medium, source, campaign, content and term
Channels and sources come from the referrer and utm_* parameters. The ref and source query parameters are also understood.