DM5: Tracking: events, tags and measurement plans

Lesson 4 of 5 · reading 15–25 minutes; practice and project time is on the module page

Campaign tags (UTM parameters)

🎯You'll be able to

Tag campaign links with UTM parameters, keep names consistent, and carry campaign information through a visit.

🏠The everyday picture

A shop hands out leaflets with a code: "Show this leaflet for 10% off: code PARK-OCT". At the till they count which leaflets brought customers.

📘What it really is

UTM parameters are added to links you control (emails, social posts, partner sites, QR codes):
utm_source: where the link is (newsletter, instagram, partner-blog);
utm_medium: the type of channel (email, social, referral, cpc);
utm_campaign: the campaign (diwali-2026);
optional utm_content (which link or creative) and utm_term (search keyword).
Example: https://www.mittimart.example/?utm_source=newsletter&utm_medium=email&utm_campaign=diwali-2026.
Naming rules: lower case, hyphens, a shared list of allowed values. Email, email and e-mail become three channels in reports.
Session attribution: the tags arrive on the landing page only. Analytics tools keep them for the visit, so later events (a purchase) are credited to the campaign. MittiMart's solved tags.js stores them in sessionStorage.
Don't tag internal links (from one MittiMart page to another): it starts a new "campaign" in the middle of a visit and breaks attribution.
Ad platforms often add their own click IDs automatically; UTMs are mostly for channels you manage yourself.
Keep UTMs free of personal data: don't put an email or phone number in a campaign tag.

📝A worked example

Input: the starter tags.js ignores UTM tags.

Steps:

On page load, read utm_source, utm_medium and utm_campaign from the address; if present, store them in sessionStorage.
Add them to every page_view as campaign_source, campaign_medium and campaign_name.
Run npm run test:tracking and read test 9.

Expected output: both page views in the test visit (the tagged home page, then the shop page) carry newsletter, email and diwali-2026.

🌍Where it's used

Email teams tag every link in a newsletter.
Social teams tag links in posts and profile bios.
Offline campaigns put tagged links in QR codes on posters and packaging.

📝Case scenario

A cosmetics brand's influencers each made up their own tags: "Insta", "instagram", "IG", "insta_story". The campaign report showed 23 "sources". A shared spreadsheet that generated links from fixed lists solved it for the next campaign.

🖱️Try it

Write tagged links for MittiMart's shop page for three channels: the newsletter, an Instagram bio, and a QR code on packaging. Success: lower case, consistent medium values (email, social, offline or similar), and one campaign name.

⚠️Common mistakes

Inconsistent spelling. Sign: Email and email as separate channels. Fix: a fixed list and a link builder.
Tagging internal links. Sign: a visit "restarting" in reports. Fix: tag only links from outside the site.
Dropping tags after the first page. Sign: purchases credited to "direct". Fix: keep campaign values for the visit.

🛠️For your project

Project 1's test 9 opens a tagged link, then another page, and checks both page views carry the campaign.

✅Quick check

Which three UTM parameters are most used?

Show the answer

utm_source, utm_medium and utm_campaign.

Should links between pages of your own site carry UTM tags?

Show the answer

No; they restart attribution in the middle of a visit.