#4671: document that pydoc imports modules.
diff --git a/Doc/library/pydoc.rst b/Doc/library/pydoc.rst
index 6d4986e..3784515 100644
--- a/Doc/library/pydoc.rst
+++ b/Doc/library/pydoc.rst
@@ -36,6 +36,13 @@
Unix), and refers to an existing Python source file, then documentation is
produced for that file.
+.. note::
+
+ In order to find objects and their documentation, :mod:`pydoc` imports the
+ module(s) to be documented. Therefore, any code on module level will be
+ executed on that occasion. Use an ``if __name__ == '__main__':`` guard to
+ only execute code when a file is invoked as a script and not just imported.
+
Specifying a :option:`-w` flag before the argument will cause HTML documentation
to be written out to a file in the current directory, instead of displaying text
on the console.