The reference list below covers the medium values working marketers actually use, grouped by channel family, each with a one-line definition and GA4 notes where relevant. Use it as the raw material for your team's controlled vocabulary — then delete everything you will never run.
Paid search
cpc— cost-per-click search ads (Google Ads, Bing Ads). The canonical paid-search medium; GA4 maps it to Paid Search.ppc— pay-per-click, the older synonym. Functionally identical to cpc: pick one, never both.
Paid social
paid-social— paid ads on social platforms, kebab-case. The most widely documented form.paid_social— snake_case twin. Same meaning; the delimiter is a team decision.social-paid— reversed order some taxonomies prefer. Fine if consistent.
Organic social
social— unpaid social posts. Short and GA4-recognized.organic-social— explicit form that cannot be confused with paid social.organic— unpaid search when tagged manually (search engines usually pass this automatically).
Email, SMS & messaging
email— newsletters, drip sequences, broadcasts. GA4 maps it to the Email channel.sms— text-message campaigns; GA4 recognizes it as its own grouping.push— mobile or web push notifications.in-app— in-app messages driving a new session.
Display & video
display— banner and programmatic display; GA4's Display channel.banner— explicit banner format, for teams that split display by creative type.cpm— impression-billed buys, social or display.video— video ads on YouTube, Vimeo and similar.
Partners & earned
affiliate— commission-based partner traffic.partner— co-marketing and integration links that are not commission-based.referral— earned links: guest posts, press, directories.podcast— sponsorships and show-note links.audio— streaming-audio ads and smart-speaker spots.
Offline
qr— QR codes on print, packaging and booths.print— magazines, flyers, direct mail.offline— catch-all bucket for non-digital touchpoints.
From list to taxonomy
A reference list is not a taxonomy — a taxonomy is the short list your team actually enforces. Generate a tailored set for your channels with the free generator, keep it under a dozen values, and review every new campaign against it.