Merge remote-tracking branch 'upstream/main' into series-sum-attrs

Author: fbourgey

Diff for: pandas/core/dtypes/base.py

@@ -45,6 +45,11 @@ class ExtensionDtype:
     """
     A custom data type, to be paired with an ExtensionArray.
 
+    This enables support for third-party and custom dtypes within the
+    pandas ecosystem. By implementing this interface and pairing it with a custom
+    `ExtensionArray`, users can create rich data types that integrate cleanly
+    with pandas operations, such as grouping, joining, or aggregation.
+
     See Also
     --------
     extensions.register_extension_dtype: Register an ExtensionType