Final answer:
Retailing is primarily about selling goods on the internet, which is part of the tertiary sector that encompasses a variety of service-based activities, particularly in the vast field of eCommerce.
Step-by-step explanation:
Retailing is the primary activity in selling goods on the internet. This falls under the tertiary economic sector, which includes services rather than the production of physical goods. The activities in the tertiary sector, which make up a substantial part of the GDP, involve distributing, selling, and enabling consumers to purchase the products.
With advancements in technology and globalization, retailing has expanded to include online platforms, which have increased competition in local markets and allowed for a broader reach to customers worldwide.