The anology between clients and servers can best be thought of as similar to the exchange between the guest at a hotel, and their interaction with the concierge desk. The concierge has access to the various resources the guest may need such as making dinner reservations or getting opera tickets. When the guest gets to the desk, they are typically in need of information, which the concierge then provides based upon their request.
    In the interaction between a client and server, the client (a web browser) is making requests to the entity with the access to the information needed: the backend server.