In the previous chapter, we saw that you can use cloud web services to create an information system where apps running on different devices can connect to the same data store. Not only can you use Delphi to integrate with existing web services, but you can also build your own!
Why would you build mobile backend services? Multi-tier architectures, with client apps communicating with server apps to access underlying resources, have a lot of benefits. Additional tiers make the app architecture more complex, and they also bring benefits such as improved scalability and security. The multi-tier approach simplifies change management, because client apps are not tied to the underlying services and communicate with them through an abstraction layer provided by server APIs.
In multi-tier architectures, the actual server app is just one of the many pieces...