The PostgreSQL system architecture is a typical client/server model, involving a server process and the user's client. The server process, called postgres, is responsible for managing the database files, receiving connection requests from clients, and performing data operations on demand. Client applications can exist in various forms, such as web clients, console clients, and graphical clients.
It is important to note that the PostgreSQL server produces processes to handle a massive number of connections at the same time by forking a new process for each connection.