Referrer
Updated 2026-11-02
Definition
A referrer is the page a visitor was on just before arriving at your site. The browser passes it along with the request, and analytics scripts read it from document.referrer.
If someone clicks a link to you from a blog post, that post's address is the referrer. Analytics tools use it to group traffic into channels such as search, social and referral.
Example
This example uses made-up numbers. In one week your site gets 5,000 visits:
| Referrer host | Visits | Channel |
|---|---|---|
www.google.com | 2,400 | Organic search |
www.linkedin.com | 700 | Organic social |
someblog.com | 400 | Referral |
| None | 1,500 | Direct |
Most browsers send only the host for cross-site links, so you see www.google.com and not the search query. That's why you can't read Google keywords from your analytics.
When the referrer goes missing
- Links in mobile apps, email clients and desktop apps often send none.
- A link with
rel="noreferrer"sends none. - A strict referrer policy on the linking site can remove it.
- A move from an HTTPS page to an HTTP page removes it.
Visits with no referrer usually land in direct traffic, which is one reason direct is often inflated.
How Headstream measures it
The Headstream script sends document.referrer with each event. The host is stored as referrer_host, which is a breakdown you can filter by. For attribution, a session's channel comes from its first pageview.
Referrers from known search engines become organic search, referrers from known social sites become organic social, and known AI tools such as ChatGPT, Claude and Perplexity become AI search. Any other outside host is referral. Click IDs and UTM parameters take priority over the referrer in most cases. A referrer from your own site doesn't count as a source.