Mercari is a popular online marketplace that allows users to buy and sell new and used items. Founded in Japan in 2013, it has expanded to the United States and other countries, providing a platform for individuals to list items for sale easily. Users can browse various categories, including clothing, electronics, and home goods. The app is user-friendly, enabling sellers to upload photos and descriptions of their items quickly. Buyers can communicate with sellers, negotiate prices, and make secure transactions. Mercari also offers shipping options and buyer protection, making it a convenient choice for online shopping.