DOC: Reintroduce glossary (matplotlib#30782)

* DOC: Reintroduce glossary

Closes matplotlib#28889.

* Apply suggestions from code review

Co-authored-by: Elliott Sales de Andrade <quantum.analyst@gmail.com>

* Apply suggestions from code review

Co-authored-by: hannah <story645@gmail.com>

---------

Co-authored-by: Elliott Sales de Andrade <quantum.analyst@gmail.com>
Co-authored-by: hannah <story645@gmail.com>

Author: 3 people

doc/users/glossary.rst

@@ -0,0 +1,44 @@
+========
+Glossary
+========
+
+.. Note for glossary authors:
+   The glossary is primarily intended for Matplotlib's own concepts and
+   terminology, e.g. figure, artist, backend, etc. We don't want to list
+   general terms like "GUI framework", "event loop" or similar.
+   The glossary should contain a short definition of the term, aiming at
+   a high-level understanding. Use links to redirect to more comprehensive
+   explanations and API reference when possible.
+
+This glossary defines concepts and terminology specific to Matplotlib.
+
+.. glossary::
+
+    Figure
+        The outermost container for a Matplotlib graphic. Think of this as the
+        canvas to draw on.
+
+        This is implemented in the class `.Figure`. For more details see
+        :ref:`figure-intro`.
+
+    Axes
+        This is a container for what is often colloquially called a plot/chart/graph.
+        It's a data area with :term:`Axis`\ es, i.e. coordinate directions,
+        and includes data artists like lines, bars etc. as well as
+        decorations like title, axis labels, legend.
+
+        Since most "plotting operations" are realized as methods on `~.axes.Axes`
+        this is the object users will mostly interact with.
+
+        Note: The term *Axes* was taken over from MATLAB. Think of this as
+        a container spanned by the *x*- and *y*-axis, including decoration
+        and data.
+
+    Axis
+        A direction with a scale. The scale defines the mapping from
+        data coordinates to screen coordinates. The Axis also includes
+        the ticks and axis label.
+
+    Artist
+        The base class for all graphical element that can be drawn.
+        Examples are Lines, Rectangles, Text, Ticks, Legend, Axes, ...

doc/users/index.rst

@@ -103,3 +103,4 @@ Using Matplotlib
 
     getting_started/index
     ../install/index
+    glossary