Referral traffic is used to describe visitors to your site that come from direct links on other websites rather than directly or from searches.

Referral marketing is a method of promoting products or services to new customers through referrals, usually word of mouth. Such referrals often happen spontaneously but businesses can influence this through appropriate strategies.

Referral link is a link that is given out to each customer who is invited to participate your referral program.

A Referral link is just a link on a website. One someone clicks on it and they end up on your website it's called a referral.