Amazon
Amazon is the world's largest online marketplace, dealing in physical and digital goods, and also involved in cloud computing and AI.
Apple iTunes
iTunes is Apple's media store, selling songs, albums, books, audiobooks, movies, and TV shows.
Walmart
Walmart is a multinational retail chain that sells a variety of products at low prices. They are known for their "greeters" that help shoppers find products in their brick-and-mortar stores.