from the help section:
You can drive traffic from oustide of HubPages to the Hubs of other Hubbers and receive a percentage of the overall impressions. The traffic referral program works the following way:
We start with Unique Trackers
Every HubPages account has its own default referral tracker – referred to as a Unique Tracker. You can create additional referral trackers as you organize your link campaigns.
Use the Unique Tracker to link to someone’s Hub.
Before you can link, you must be signed in to HubPages. Then, when you’re at the Hub you want to link to, look at the bottom of the page (or click the green share it button). There will be two boxes marked “link to this page” and “email this page”. You can click on these links and choose the Unique Tracker you want to insert in the email, URL or HTML code we will generate for you. From that point, you can either send the mail, or cut and paste the URL link or HTML code and place it wherever you’d like outside of HubPages.
The Traffic Referrals is guaranteed to be yours for 120 minutes.
If someone clicks on your link to a specific Hub, you are entitled to the traffic referral impressions for 120 minutes. We set this limit because there may be multiple Hubbers referring people to a particular Hub. No other tracker can replace yours during that 120 minute period. This is called the ‘first dibs’ rule.