An affiliate order is any order generated through an affiliate's efforts, as tracked by a discount code or unique link. For example, if an affiliate is promoting your site with their discount code, and a visitor uses that discount code when purchasing a product from your site, that counts as an affiliate order.
Affiliates promote your products in exchange for a commission of the sales they bring you. As the store owner, you have the ability to customize the commission amount (fixed rate or percentage) that you will pay your affiliates.
With Social Snowball, every customer that makes a purchase on your store will automatically become an affiliate, and will have a discount code generated for them to share to their friends, family, and followers!