diff --git a/Lib/pathlib.py b/Lib/pathlib.py
index 73dd513..8431c29 100644
--- a/Lib/pathlib.py
+++ b/Lib/pathlib.py
@@ -584,7 +584,9 @@
 
 
 class PurePath(object):
-    """PurePath represents a filesystem path and offers operations which
+    """Base class for manipulating paths without I/O.
+
+    PurePath represents a filesystem path and offers operations which
     don't imply any actual filesystem I/O.  Depending on your system,
     instantiating a PurePath will return either a PurePosixPath or a
     PureWindowsPath object.  You can also instantiate either of these classes
@@ -939,11 +941,21 @@
 
 
 class PurePosixPath(PurePath):
+    """PurePath subclass for non-Windows systems.
+
+    On a POSIX system, instantiating a PurePath should return this object.
+    However, you can also instantiate it directly on any system.
+    """
     _flavour = _posix_flavour
     __slots__ = ()
 
 
 class PureWindowsPath(PurePath):
+    """PurePath subclass for Windows systems.
+
+    On a Windows system, instantiating a PurePath should return this object.
+    However, you can also instantiate it directly on any system.
+    """
     _flavour = _windows_flavour
     __slots__ = ()
 
@@ -952,6 +964,14 @@
 
 
 class Path(PurePath):
+    """PurePath subclass that can make system calls.
+
+    Path represents a filesystem path but unlike PurePath, also offers
+    methods to do system calls on path objects. Depending on your system,
+    instantiating a Path will return either a PosixPath or a WindowsPath
+    object. You can also instantiate a PosixPath or WindowsPath directly,
+    but cannot instantiate a WindowsPath on a POSIX system or vice versa.
+    """
     __slots__ = (
         '_accessor',
         '_closed',
@@ -1427,9 +1447,17 @@
 
 
 class PosixPath(Path, PurePosixPath):
+    """Path subclass for non-Windows systems.
+
+    On a POSIX system, instantiating a Path should return this object.
+    """
     __slots__ = ()
 
 class WindowsPath(Path, PureWindowsPath):
+    """Path subclass for Windows systems.
+
+    On a Windows system, instantiating a Path should return this object.
+    """
     __slots__ = ()
 
     def owner(self):