Online marketplaces are virtual platforms where various sellers can list their products or services, and buyers can browse and purchase them. These platforms provide a centralized environment where transactions occur, usually involving a secure payment system integrated into the platform. They can range from general-purpose marketplaces like Amazon and eBay to niche-specific sites focusing on specific categories such as Etsy for handmade goods or Udemy for online courses. Online marketplaces have transformed traditional commerce by enabling direct access to a broad audience and reducing the overhead costs for sellers compared to running their own independent online sales channels.