single class dictionary lookup is negligible.
+Type Annotation Types --- :ref:`Generic Alias <types-genericalias>`, :ref:`Union <types-union>`
+===============================================================================================
+
+.. index::
+ single: annotation; type annotation; type hint
+
+The core built-in types for :term:`type annotations <annotation>` are
+:ref:`Generic Alias <types-genericalias>` and :ref:`Union <types-union>`.
+
+
.. _types-genericalias:
Generic Alias Type
-==================
+------------------
.. index::
object: GenericAlias
Standard Generic Collections
-----------------------------
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^
These standard library collections support parameterized generics.
Special Attributes of Generic Alias
------------------------------------
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
All parameterized generics implement special read-only attributes.
.. _types-union:
Union Type
-==========
+----------
.. index::
object: Union