diff --git a/src/typing_extensions.py b/src/typing_extensions.py
index cce31f8..8fee27f 100644
--- a/src/typing_extensions.py
+++ b/src/typing_extensions.py
@@ -440,7 +440,50 @@ else:
 Counter = typing.Counter
 ChainMap = typing.ChainMap
 AsyncGenerator = typing.AsyncGenerator
-NewType = typing.NewType
+if sys.version_info >= (3, 10):
+    NewType = typing.NewType
+else:
+    class _NewType:
+        def __init__(self, name, tp):
+            if not isinstance(name, str):
+                raise TypeError("NewType name must be a string")
+            if not isinstance(tp, type):
+                raise TypeError("NewType must be called with a type")
+            self.name = name
+            self.tp = tp
+            # Create the actual type that will be used
+            def __new__(cls, value):
+                return tp(value)
+            # Determine module for pickling
+            module = sys._getframe(1).f_globals.get('__name__', '__main__')
+            # Build the type
+            self._super = tp
+            self._type = type.__new__(
+                type, name, (tp,), {
+                    '__module__': module,
+                    '__name__': name,
+                    '__new__': staticmethod(__new__),
+                    '__reduce__': lambda self: (_NewType, (name, tp)),
+                }
+            )
+        def __call__(self, value):
+            return self._type(value)
+        def __reduce__(self):
+            return (_NewType, (self.name, self.tp))
+        # For attributes access
+        def __getattr__(self, item):
+            return getattr(self._type, item)
+        def __repr__(self):
+            return f"{self._type.__module__}.{self.name}"
+        # Prevent subclassing instances
+        def __init_subclass__(cls, **kwargs):
+            raise TypeError(
+                "Cannot subclass an instance of NewType. Perhaps you were looking for: "
+                "`ProUserId = NewType('ProUserId', UserId)"
+            )
+
+    def NewType(name, tp):
+        return _NewType(name, tp)
 Text = typing.Text
 TYPE_CHECKING = typing.TYPE_CHECKING