Amazon is one of the bigger publishers of electronic books and has developed multiple electronic ebook devices (kindle). Questions tagged amazon can include publishing policies, ebooks available at Amazon. Device specific questions should be tagged "Kindle".
Amazon is the world largest online retailer and was founded by Jeff Bezos. It went online in 1995, initially selling books, later adding additional products and becoming a generic retailer.
Amazon has been selling their Kindle ebook reading devices since 2007. Although they sell other (EPUB) format ebooks as well, their main focus is on ebooks for the Kindle devices.