DOCSP-33543-datetime-enhancements (#5272) (#5312)

* DOCSP-33543-datetime-enhancements

* DOCSP-33543-datetime-enhancements

* DOCSP-33543-datetime-enhancements

* DOCSP-33543-datetime-enhancements

* DOCSP-33543-datetime-enhancements

* DOCSP-33543-datetime-enhancements

---------

Co-authored-by: jason-price-mongodb <[email protected]>

Author: jason-price-mongodb

source/reference/method/Date.txt

@@ -1,6 +1,6 @@
-======
-Date()
-======
+===================
+Date() and Datetime
+===================
 
 .. default-domain:: mongodb
 
@@ -13,7 +13,14 @@ Date()
 .. method:: Date()
 
    Returns a date either as a string or as a
-   :ref:`document-bson-type-date` object.
+   :ref:`document-bson-type-date` object. The date can contain a date
+   and a time, known as a *datetime*.
+
+   The `BSON specification <http://bsonspec.org/#/specification>`_
+   states a ``Date`` object contains the *UTC datetime*. UTC is
+   *Coordinated Universal Time*. The UTC datetime stores an unsigned
+   64-bit integer value, indicating the number of milliseconds after the
+   Unix epoch (January 1st, 1970 at 00:00:00 UTC).
 
 Compatibility
 -------------
@@ -87,13 +94,11 @@ collection, the following operation inserts a document with the field
    - :update:`$currentDate`
    - :ref:`NOW aggregation variable usage <currentDate-example-agg>` to
      update with aggregation pipeline 
-   
 
 Return Date as a String
 ~~~~~~~~~~~~~~~~~~~~~~~
 
-To return the date as a string, use the ``Date()`` method, as in the
-following example:
+To return the date as a string, use the ``Date()`` method. For example:
 
 .. code-block:: javascript
 
@@ -103,11 +108,11 @@ Return Date as ``Date`` Object
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 :binary:`~bin.mongosh` wraps objects of
-:ref:`document-bson-type-date` type with the ``ISODate`` helper;
-however, the objects remain of type :ref:`document-bson-type-date`.
+:ref:`document-bson-type-date` type with the ``ISODate`` helper.
+However, the objects are :ref:`document-bson-type-date` types.
 
 The following example uses ``new Date()`` to return
-:ref:`document-bson-type-date` object with the specified UTC datetime.
+a :ref:`document-bson-type-date` object with the specified UTC datetime:
 
 .. code-block:: javascript