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+[[!meta copyright="Copyright © 2002, 2003, 2010 Free Software Foundation,
+Inc."]]
+
+[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable
+id="license" text="Permission is granted to copy, distribute and/or modify this
+document under the terms of the GNU Free Documentation License, Version 1.2 or
+any later version published by the Free Software Foundation; with no Invariant
+Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license
+is included in the section entitled [[GNU Free Documentation
+License|/fdl]]."]]"""]]
+
+A Mach *task* is a collection of resources, a [[virtual_address_space]], and a
+[[port name space|port]]. They depend on [[thread]]s for executing program
+code: a task alone has no means to do so.
+
+Switching from one task to another one involves doing a *context switch*, which
+is usually not a cheap operation, as it involves switching the hardware's idea
+of the memory layout ([[virtual_address_space]]), amongst others.
+
+Mach tasks are distinct from [[UNIX processes|unix/process]] in that they
+provide less facilities. In processes, there are [[unix/signal]]s, process /
+group / session IDs, [[unix/file_descriptor]]s and many other things. Tasks
+are used for resource allocation and sharing; they are *resource container*s.