The General Data Protection Regulation (GDPR), which took effect on May 25, 2018, is a set of regulations governing the use of personal data across the EU. This is forcing some affiliates to obtain user data through opt-in consent (updated privacy policies and cookie notices), even if they are not located in the European Union. This new regulation should also remind you to follow FTC guidelines and clearly disclose that you receive affiliate commissions from your recommendations.
Affiliate marketing is also called "performance marketing", in reference to how sales employees are typically being compensated. Such employees are typically paid a commission for each sale they close, and sometimes are paid performance incentives for exceeding objectives. Affiliates are not employed by the advertiser whose products or services they promote, but the compensation models applied to affiliate marketing are very similar to the ones used for people in the advertisers' internal sales department.