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+# Distributed Systems
+
+A distributed system is a collection of processors that do not share memory or a clock.
+Each node has its own local memory.
+The nodes communicate with one another through various networks, such as high-speed buses
+and the Internet.
+
+## Network operating systems
+
+Allows users to log in remotely.
+
+```bash
+$ ssh cs.yale.edu
+```
+
+Allows remote file transfer from one host to another.
+
+
+Load balancing: The processes may be distributed across the network to even the workload.
+Computation speedup: A single process can be divided into a number of subprocesses that can run concurrently.
+Hardware preference: The process may have characteristics that make it more suitable for execution on some specialized processors.
+Software preference: The process may require software that is available at only a particular site.
+Data access: it may be more efficient to have a process run remotely than to transfer all the data.
+
+## Summary
+
+A distributed system is a collection of processors that do not share memory or a clock.
+The processors in a distributed system vary in size and function.