Affiliate marketing is a type of performance-based marketing in which a business rewards one or more affiliates for each visitor or customer brought about by the affiliate's own marketing efforts. Essentially, it involves:

1. A business (merchant or advertiser): That has a product or service to sell.
2. An affiliate (publisher): That promotes the product or service.
3. A customer: Who purchases the product or service through the affiliate's promotion.

The affiliate earns a commission for each sale, lead, or click generated through their unique affiliate link or code. This makes it a popular way for individuals and businesses to monetize their online presence, such as a blog, website, or social media account.

Key aspects of affiliate marketing:

• Performance-Based: Affiliates only get paid when a desired action (sale, lead, click) occurs.
• Wide Range of Products: Affiliates can promote products from various industries.
• Low Risk for Merchants: Merchants only pay when they get results.
• Diverse Promotional Methods: Affiliates use various methods, including content marketing, social media, email marketing, and paid advertising.

For more in-depth information, you can refer to these resources:

• Investopedia's definition of Affiliate Marketing
• Shopify's explanation of Affiliate Marketing