2nd tier. If you are an affiliate for a particular program and you refer others to sign up for that affiliate program, a 2nd tier program will pay you when the affiliates you referred make sales. For example, I am an affiliate for Ultimate Bundles. If you join their affiliate program via my 2nd tier affiliate link here. I will get a small percentage of any sales you make going forward.
Affiliate marketing overlaps with other Internet marketing methods to some degree, because affiliates often use regular advertising methods. Those methods include organic search engine optimization (SEO), paid search engine marketing (PPC – Pay Per Click), e-mail marketing, content marketing, and (in some sense) display advertising. On the other hand, affiliates sometimes use less orthodox techniques, such as publishing reviews of products or services offered by a partner.