eBay Inc. ( EE-bay, often stylized as ebay or Ebay) is an American multinational e-commerce company based in San Jose, California, that allows users to buy or view items via retail sales through online marketplaces and websites in 190 markets worldwide. Sales occur either via online auctions or "buy it now" instant sales, and the company charges commissions to sellers upon sales. eBay was founded by Pierre Omidyar in September 1995. It has 132 million yearly active buyers worldwide and handled $73 billion in transactions in 2023, 48% of which was in the United States. In 2023, the company had a take rate (revenue as a percentage of volume) of 13.81%.

eBay can be used by individuals, companies and governments to purchase and sell almost any legal, non-controversial item. eBay's auctions use a Vickrey auction (sealed-bid) proxy bid system. Buyers and sellers may rate and review each other after each transaction, resulting in a reputation system. The eBay service is accessible via websites and mobile apps. Software developers can create applications that integrate with eBay through the eBay API. Merchants can also earn commissions from affiliate marketing programs by eBay.