Client-Server Model – describes the communication between two computing entities over a network. Clients are the ones requesting a resource or service and Servers are the ones providing that resource or service. Note, the server can be running one or more programs and involved in multiple communications with multiple clients at the same time. The client initiates the communication and awaits a response from the server. This model was developed in the ‘70s at Xerox Palo Alto Research Center (PARC).