An http referrer or referrer is anything online that drives visits and visitors to your Web site. This can include:
- search engines
- link lists
- banner ads
- affiliate links
- links built into software
Technically, even offline sources like print ads or references in books or magazines are referrers, but these aren't specifically captured in the server referrer log. When a Web developer uses the term "referrer" she means those sites or services that are referenced in the Web server logs.
Just Tracking Referrers is Harder Than it Seems
You would think, that because referrers are recorded in the server log (combined log format) of most Web servers that they would be easy to track. But there are some big hurdles to overcome:
- Search engines provide information in their referring URL such as search terms used or the directory section the customer was in. This means that the URL is usually more complicated than simply
And, once that information is there, chances are you'll want to know what terms people are searching for and finding your site, so you need to parse that information.
- On the other extreme, email links and links from software may not provide much information at all on the referring URL. (In fact, some software and email clients deliberately mask the referrer, so that you can't track them.) To get around this, you should include something in the URL that identifies it as an email or software link. For example:
Not all log entries have referring URLs listed in the entry. This can mean several things:
- The customer typed in the URL by hand
- The customer had the page bookmarked
- The customer was using privacy protection software that blocked the referrer
Where is the Referrer Stored?
Web server logs track the referrer, but you have to set up your logs to be in Combined Log Format. The following is a log entry in Combined Log Format, with the referrer bolded:
10.1.1.1 - - [08/Feb/2004:05:37:49 -0800] "GET /cs/loganalysistools/a/aaloganalysis.htm HTTP/1.1" 200 2758 "http://webdesign.about.com/" "Mozilla/4.0 (compatible; MSIE 6.0; Windows 98; YPC 3.0.2)"