Source and Medium

Source and Medium are core analytics parameters that show where a visitor came from and how they got there. Together they form the foundation for measuring marketing channel performance.

Anatomy

Source: where from

Source identifies the platform or resource. A domain, search engine, social network, or any other origin.

Examples:

google, bing, duckduckgo (search engines)
facebook, instagram, linkedin (social)
example.com (referring site)
newsletter (email)
(direct) (no identifiable source)

Medium: how

Medium defines the channel type or delivery method. Source answers "from where". Medium answers "how".

Standard values:

Medium	Description	Use case
organic	Organic search	Unpaid search results
cpc/ppc	Pay-per-click	Contextual advertising
referral	Referral link	Transition from another site
email	Email distribution	Email links
social	Organic social	Organic social posts
display	Display advertising	Banner advertising
affiliate	Partner traffic	Partner links
(none)	Undefined	Direct visits

Source/Medium and UTM

UTM parameters set Source and Medium explicitly for any link.

UTM link structure

example.com/landing?utm_source=facebook&utm_medium=cpc&utm_campaign=summer_sale

utm_source=facebook: traffic from Facebook
utm_medium=cpc: paid pay-per-click
utm_campaign=summer_sale: summer sale campaign

Full UTM structure

Parameter	Required	Purpose	Example
utm_source	Yes	Source	facebook, google, newsletter
utm_medium	Yes	Channel type	cpc, email, social
utm_campaign	Yes	Campaign name	product_launch_2025
utm_content	No	Ad variant	banner_blue, text_link
utm_term	No	Keyword	web_analytics

Auto-detection vs manual tagging

Analytics systems try to detect Source and Medium for untagged traffic.

Auto-detection works for:

Organic search (recognized engines)
Referral traffic (extracted source domain)
Direct visits (no referrer)

Manual tagging required for:

Ad campaigns (accurate attribution)
Email distributions (otherwise fall into Direct)
Social (separate paid and organic)
Partner programs (track partner performance)

Tagging rules

Naming standardization

Consistency is everything.

Common mistakes

Case issues:

Wrong: Facebook, facebook, FACEBOOK (three sources)
Right: facebook

Inconsistent names:

Wrong: fb, facebook, Facebook_ads
Right: facebook

Spaces in parameters:

Wrong: utm_medium=paid social (truncates to "paid")
Right: paid_social

Detail hierarchy

Different detail levels enable analysis at different depths.

BasicAdvancedExpert

Minimal detail for general analysis:

utm_source=facebook
utm_medium=paid

Detail for deeper analysis:

utm_source=facebook_feed
utm_medium=cpc_retargeting

Maximum detail:

utm_source=facebook_lookalike_us
utm_medium=cpc_conversion_optimized

Documentation

Source/Medium documentation is mandatory for team work.

Documentation template

Social:

Facebook organic: source=facebook, medium=social
Facebook ads: source=facebook, medium=cpc
Instagram Stories: source=instagram, medium=stories

Email:

Newsletter: source=newsletter, medium=email
Trigger: source=automation, medium=email
Promo: source=promo, medium=email

Partner programs:

Main partners: source=[partner_name], medium=affiliate
Referral links: source=[referrer_name], medium=referral

Performance analysis

Key metrics

Metric	What it shows	Read
Sessions	Volume	Source popularity
Bounce Rate	Relevance	Targeting quality
Conversion	Effectiveness	ROI potential
AOV	Visitor value	LTV forecast
Time on Site	Engagement	Content quality for the audience

Segmentation

graph TD
    A[Source/Medium Data] --> B{Segmentation}
    B --> C[By Device]
    B --> D[By Geography]
    B --> E[By Time]
    B --> F[By Landing Pages]

    C --> G[Mobile vs Desktop]
    D --> H[Countries and Regions]
    E --> I[Days and Hours]
    F --> J[Page Effectiveness]

Multi-channel funnels

Source/Medium reveals the full journey.

B2B conversion path

First touch: google / organic (solution search)
Research: linkedin / social (company research)
Comparison: capterra.com / referral (reading reviews)
Return: (direct) / (none) (direct visit)
Conversion: newsletter / email (purchase after email)

Email gets the conversion, but organic search started the journey.

Source/Medium by channel

Paid advertising

Accurate tagging is critical for ROI.

Google Ads:

utm_source=google
utm_medium=cpc
utm_campaign={campaign_name}
utm_content={ad_id}
utm_term={keyword}

Facebook Ads:

utm_source=facebook
utm_medium=paid_social
utm_campaign={campaign_name}
utm_content={ad_set_name}

Organic channels

Even free traffic needs tagging.

Blog and content marketing:

utm_source=blog
utm_medium=article
utm_campaign=seo_content
utm_content=guide_analytics

Organic social:

utm_source=linkedin
utm_medium=social_organic
utm_campaign=thought_leadership

Email marketing

Email without UTM falls into Direct, distorting reality.

Email structure

Welcome series:

utm_source=welcome_series
utm_medium=email
utm_campaign=onboarding
utm_content=email_{number}

Promo newsletter:

utm_source=promo_newsletter
utm_medium=email
utm_campaign=black_friday_2025
utm_content={link_position}

Limits

Standard platform limits

Parameter length limits: long values truncate
Attribution loss: cross-domain transitions
Retroactive analysis: can't reclassify historical data
Limited customization: rigid grouping rules

Where Statable stands

Statable shares most of those limits, and it is worth knowing which.

Classification is rule-based, not learned. Source and medium come from the referrer and the URL parameters, nothing else. No model infers the origin of an untagged visit from behaviour, so an untagged email link still lands in Direct.
Grouping is fixed. Channels cannot be redefined per site, and history is not reclassified when you change how you tag.
One attribution model. There is no switch between first-touch, last-touch and the rest. Each session keeps the source it arrived with, and a referrer seen later in the same session does not overwrite it.
No UTM generator. Build your links with any of the tools above.

What you get without any setup: all five UTM parameters read, source and ref accepted as spellings of utm_source, known search engines and referrers resolved to a readable name, and ten advertising click ids recognised so a paid visit is not filed as organic.

Practical recommendations

Launch checklist

Tools

UTM link generators:

Reduce errors. Keep tagging consistent.

Bulk generation spreadsheets:

Excel or Google Sheets formulas auto-create tagged URLs for big campaigns.

Automation systems:

Integrate with ad platforms for dynamic parameter substitution.

Future

Privacy regulation

Referrer blocking: browsers restrict source transmission
Intelligent Tracking Prevention: auto-removes tracking parameters
Consent-based tracking: explicit consent required

Adapting

Server-side tracking bypasses browser limits.

First-party attribution uses your own data and identifiers.

Probabilistic attribution applies statistical models to recover lost data.

Source/Medium is fundamental for measuring marketing performance. Multi-channel journeys and tightening privacy make it harder and more important. Investment in proper Source/Medium setup pays back in better marketing spend and clearer behavior insight.

About AI participation in writing articles

This article, like many others on our site, was created, written and proofread by a team of developers. Of course, not without the participation of AI assistants. We don't hide this and believe that modern systems are already quite good at handling simple tasks and, relatively speaking, writing an article about Viewport yourself is quite strange. It won't come out significantly better and will take a lot of time. But providing basic understanding to beginner webmasters is necessary. Of course, after the article is written by assistants - there's always proofreading, and this is where not one or two people participate, and only after that the article is published.

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