diff -r 5a9f2de4dc16 Doc/tutorial/inputoutput.rst
--- a/Doc/tutorial/inputoutput.rst	Sun Jan 03 19:37:07 2016 +0530
+++ b/Doc/tutorial/inputoutput.rst	Mon Jan 04 07:35:46 2016 +0530
@@ -271,7 +271,7 @@
 ``f`` has already been created.
 
 To read a file's contents, call ``f.read(size)``, which reads some quantity of
-data and returns it as a string or bytes object.  *size* is an optional numeric
+data and returns it as a string (in text mode) or bytes object (in binary mode).  *size* is an optional numeric
 argument.  When *size* is omitted or negative, the entire contents of the file
 will be read and returned; it's your problem if the file is twice as large as
 your machine's memory. Otherwise, at most *size* bytes are read and returned.
@@ -315,8 +315,7 @@
    >>> f.write('This is a test\n')
    15
 
-To write something other than a string, it needs to be converted to a string
-first::
+To write something other than a string (in text mode) or bytes object (in binary mode), it needs to be converted first to string or bytes object respectively. ::
 
    >>> value = ('the answer', 42)
    >>> s = str(value)