A lot of larger servers use social media (Such as Youtubers) to advertise their community and gain additional players to their network. The referral system allows you to generate unique links which you can provide to these influencers. Once a player uses the link that is given to them, you can view statistics such as how many times the link has been clicked and the resulting sales from the specific influencer.
Go to Engagement > Webstore Referrals.
Click Create Webstore Referral Page.
Enter the following options:
Name - An identifier for the referral link. This is only visible to you and is normally the name of the influencer or referral that you are giving the link to.
Slug - This is the text which appears in the URL of your referral link. It's normally also the name of the influencer.
Once you've entered the options above you can click create and you'll be redirected to the referral overview page. From here you can see useful information such as the full link you can give to your influencer, and also statistics such as how many people have been sent to the link and the resulting sales.