<br/>
<br/>
-Describing your Virtual Platform
-================================
+Describing your Simulated Platform
+##################################
+
+In SimGrid, platforms are usually described in XML. This formalism has
+some drawbacks, but using a specific format ensures that the platform
+is not mixed with the tested application. This separation of concern
+:ref:`is a must <howto_science>` for your Modeling and Simulation (M&S)
+work. When XML is too limiting, you may describe your platforms using
+the :ref:`lua bindings <platform_lua>` (it is not yet possible to do so in
+python or directly in C++).
+
+Since we know that writing platform description files is not trivial,
+we included :ref:`many examples <platform_examples>` in the archive. This
+documentation also contains some :ref:`hints and howtos <howto>`, as well
+as the full :ref:`XML reference guide <platform_reference>`.
+
+
+Any simulated platform must contain **basic elements**, such as hosts,
+links, storages, etc. SimGrid gives you a great liberty when defining
+**routing of your platform**, ie the path taken between each pair of
+hosts. Finally, you may also describe an **experimental scenario**,
+with qualitative changes (e.g., bandwidth changes representing an
+external load) and qualitative changes (representing how some elements
+fail and restart over time).
+
+Defining Basic Elements
+***********************
+
+There is not much to say about the definition of basic elements. Just
+use the appropriate tags: :ref:`pf_tag_host`, :ref:`pf_tag_link` and
+:ref:`pf_tag_storage`.
+
+Defining a Routing
+******************
+
+Performance Profiles and Churn
+******************************
+
+.. LocalWords: SimGrid
