Distributed computing systems evolved from 1960s mainframe time-sharing to modern cloud and edge architectures. Early foundations included ARPANET (1960s) and Ethernet (1970s), with the 1980s establishing distributed computing as a formal field. Growth was driven by client-server models, the World Wide Web, peer-to-peer (P2P) networks, and current warehouse-scale cloud computing.  Key Historical Eras in Distributed Computing 1960s – 1970s (Foundations): Time-Sharing Systems: Mainframes allowed multiple local, teletype terminal users. Early Networking: ARPANET (precursor to the Internet) began in the late 1960s, with e-mail appearing in the early 1970s. First Distributed Programs: Creeper and Reaper (1970s) tested network-based replication.