Marketplaces are all over the internet. Many tech companies run them. Amazon is a marketplace for goods, and food delivery apps like DoorDash or GrubHub are marketplaces for food. While these seem completely different, they are the exact same business. They are marketplaces with all the user data, and control delivery of goods or food.
Amazon started as an online bookstore, and today sells everything from A to Z. It sells Amazon Kindle and Alexa, and third party products like cellphone cases, desk lamps, and kitchen bowls. It is a marketplace. Amazon operates the website (where the customers interact), and deals with logistics of delivery. In the middle, you have third party companies providing goods to Amazon like the cellphone cases and desk lamps. Over the years, Amazon has collected data about what users buy, and built its recommendation engine to suggest other things customers could buy too. As it got more data, Amazon now knows what customers want before the customer figures out that they need something. Amazon has used this insight into demand for products and launched its own line of products in some categories. This is their Amazon Basics brand. Amazon controls the marketplace, the user data, and delivery. It does not need the third party for goods when it can make the goods itself. At least for high demand items that it knows will fly off the virtual shelves. This has created some concerns as third parties spend their money making different products, and when a product becomes successful, an Amazon Basics clone is available instantly. It also appears as the top result on Amazon! This has caused some anti-trust concerns.