diff --git a/source/glossary.rst b/source/glossary.rst
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@@ -0,0 +1,82 @@
+Glossary
+========
+
+Settings
+--------
+
+
+.. glossary::
+
+    Actor
+        Any application connected to the bus is seen as one of several actors.
+        Each can be an :term:`Emitter`, a :term:`Consumer` or a :term:`Worker`.
+
+        An actor is always associated to a :term:`Actor Account`, so the
+        application is properly identified by the bus.
+
+    Account
+        An account is what allows a person or an application to connect to the
+        bus. There are several kinds of accounts: :term:`Actor Account`,
+        :term:`User Account` and :term:`Gateway Account`
+
+    Actor Account
+        Associated to one or several actors, it is used by :ref:`xbus-client <program-xbus-client>` or
+        other connectors to connect to xbus.
+
+    User Account
+        Used by users of the :ref:`xbusctl <program-xbusctl>` command, or the
+        web interface. It allows configuration of the pipelines, accounts,
+        actors and pipelines, as well as viewing, and acting on processes.
+
+    Gateway Account
+        An account with very specific privileges needed by a gateway program
+        like :ref:`xbus-http <program-xbus-http>`.
+
+    Pipeline
+        A pipeline defines a path between an emitter, workers and consumers.
+        It 'matches' incoming envelopes based on the message types they contain.
+
+
+Contents
+--------
+
+.. glossary::
+    Message
+        A message is what applications connected to the bus send and receive. A
+        message must have a type, which can be any alphanumeric string, and a
+        body that can be anything. A big body will be chunked for transfers.
+
+        It is identified by a GUID.
+
+    Envelope
+        An envelope is a container for :term:`messages <Message>`. It can
+        contain any positive number of messages.
+
+        It is identified by a GUID.
+
+
+
+Process
+-------
+
+.. glossary::
+    Process
+        An incoming envelope creates a Process that will track its path within
+        the bus. The first step of a process is to match a :term:`Pipeline` in
+        order to known which path should be followed.
+
+        Each process has a status, that can be one of :term:`RUNNING`,
+        :term:`PAUSED`, :term:`DONE` and :term:`ERROR`.
+
+    RUNNING
+        The status of a process that is not yet over. No error has occured, and
+        some actors still need to work or are working.
+
+    PAUSED
+        The status of a process that has been paused by the operator.
+
+    DONE
+        The status of a process that successfully runned.
+
+    ERROR
+        The status of a process in which an error occured.
diff --git a/source/index.rst b/source/index.rst
index c5d1579a6f498bd324cc89adedfe082939448613_c291cmNlL2luZGV4LnJzdA==..682d886883d51d2e394028b55b54e06fbc614988_c291cmNlL2luZGV4LnJzdA== 100644
--- a/source/index.rst
+++ b/source/index.rst
@@ -25,9 +25,10 @@
    coding-rules
    HISTORY
    releasenotes/index
+   glossary
 
 
 
 Indices and tables
 ==================
 
@@ -28,9 +29,7 @@
 
 
 
 Indices and tables
 ==================
 
-* :ref:`genindex`
-* :ref:`modindex`
 * :ref:`search`