SEO when creating many URLs for a page that differ only by the name of the person that created the link

Question

I'm developing a referral system for my website, and the way it works now is to generate an unique URL like www.example.net/public/referral/UNIQUE_URL. This page is just a normal registry page like the one found in www.example.net/public/registry, but with the text "You were referred by: NAME_LASTNAME_OF_USER". Example:

Registry page www.example.net/public/registry

name:_________

last-name:_________

email:______

password:______

Referral page www.example.net/public/referral/UNIQUE_URL

name:_________

last-name:_________

email:______

password:______

You were referred by: NAME_LASTNAME_OF_USER

How is this going to affect the SEO of the site? It will be better to use the same registry URL with a parameter? O this parameter, imagine www.example.net/public/registry/UNIQUE_URL, will also affect the SEO?

Answer 1

When you have many URLs that have the same content but with slight differences, you can use the canonical link element to tell search engines about the duplication and tell them which URL is the preferred ("canonical") URL.

Each of your pages need to contain the following tag in the head section:

<link rel="canonical" href="http://www.example.net/public/registry" />