This is an excerpt from a draft of Chapter 9 from my forthcoming book (Husovec, Principles of the Digital Services Act (OUP, [May] 2024)). It describes the main digital ecosystem of services that are regulated by the DSA as infrastructure services, hosting services, online platforms, very large online platforms (VLOPs), and very large online search engines (VLOSEs). It summarises the first disclosures made by companies on the 17th of February 2023, the first batch of designation by the European Commission in April 2023 and explains why certain companies likely fall in or outside the DSA’s regime.