Link decoration
Why it matters Many links you click or share carry hidden tracking labels. When you paste such a link to a friend, you may be sharing a label that connects you, them and the place you found it. Cleaning links takes seconds once you know what to look for.
Think of a raffle ticket with a number on it. The ticket gets you in, but the number also tells the organiser which stall sold it to you. Decorated links work the same way: the address takes you to the page, and an extra label tells someone where the click came from.
Query string: the part of a URL after the question mark, made of name=value pairs joined by &. In https://shopa.example/shoes?size=9&colour=red the query string is size=9&colour=red.
Link decoration: adding extra query string pairs to a link so that whoever receives the click learns where it came from, or which person or advert it belongs to.
The labels you will see most
| Label | What it usually means |
|---|---|
utm_source, utm_medium, utm_campaign | Campaign tags: "this click came from the spring newsletter". Usually the same for everyone who got that link. |
fbclid | A click ID added by a large social network to outbound links. Usually unique to one click. |
gclid | A click ID from a large search and advertising company's ads. |
msclkid | A click ID from another search engine's ads. |
There is an important difference here. A utm_ tag usually describes a campaign, so it is shared by thousands of people. A click ID like gclid=Cj0KCQ7x9 is usually unique to one click, so it can tie the visit back to the exact advert, and the account, that produced it.
Why decoration became popular
As browsers began blocking third-party cookies (the next module explains them), trackers looked for another way to carry an ID from one site to the next. Putting the ID in the link itself works even when cookies are blocked, because the address is simply part of where you are going.
Cleaning a link
Here is a decorated link and its clean version:
Before: https://shopa.example/boots?colour=brown&utm_source=mail&utm_campaign=spring&gclid=Cj0KCQ7x9
After: https://shopa.example/boots?colour=brownNotice that colour=brown stayed. Some query pairs do real work: a search term, a page number, a size. Remove only the labels you recognise as tracking, then check the page still shows what you expected.
Some browsers remove known tracking labels for you in certain modes, for example Firefox in its Strict tracking protection and Safari in Private Browsing (checked October 2026). These lists cover common labels only, so cleaning a link before you share it is still a good habit.
A common misconception
"Everything after the question mark is tracking." No: many sites need their query string to work. Deleting everything can break a search or a shopping basket. Remove the labels, keep the meaning.
Try it
- Find a link in a marketing email or a social media post, but do not click it. Right-click (or long-press on a phone) and choose Copy link.
- Paste it into a plain text note, not a browser.
- Look for a question mark. List each
name=valuepair after it. - Delete any pair starting with
utm_, or namedfbclid,gclidormsclkid. If nothing is left after the question mark, delete the question mark too. - Optionally, open the cleaned link in a private window and check it still reaches the same page.
Some links do not show the real address at all: they go through a redirect address first. Later legs show how those bounce redirects work; for now, notice them.
Recap
- Link decoration adds labels such as utm_, fbclid, gclid and msclkid to a URL.
- Campaign tags are shared by many people; click IDs are usually unique to one click.
- Decoration carries an ID across sites even when cookies are blocked.
- Clean shared links by removing tracking labels and keeping the pairs the page needs.
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