diff --git a/Doc/library/base64.rst b/Doc/library/base64.rst
index 9ff065ab1be..39a466e5d36 100644
--- a/Doc/library/base64.rst
+++ b/Doc/library/base64.rst
@@ -24,7 +24,7 @@ The modern interface provides:
 
 .. function:: b64encode(s, altchars=None)
 
-   Encode a string use Base64.
+   Encode a byte string use Base64.
 
    *s* is the string to encode.  Optional *altchars* must be a string of at least
    length 2 (additional characters are ignored) which specifies an alternative
@@ -32,54 +32,54 @@ The modern interface provides:
    generate URL or filesystem safe Base64 strings.  The default is ``None``, for
    which the standard Base64 alphabet is used.
 
-   The encoded string is returned.
+   The encoded byte string is returned.
 
 
 .. function:: b64decode(s, altchars=None)
 
-   Decode a Base64 encoded string.
+   Decode a Base64 encoded byte string.
 
    *s* is the string to decode.  Optional *altchars* must be a string of at least
    length 2 (additional characters are ignored) which specifies the alternative
    alphabet used instead of the ``+`` and ``/`` characters.
 
-   The decoded string is returned.  A :exc:`TypeError` is raised if *s* were
+   The decoded byte string is returned.  A :exc:`TypeError` is raised if *s* were
    incorrectly padded or if there are non-alphabet characters present in the
    string.
 
 
 .. function:: standard_b64encode(s)
 
-   Encode string *s* using the standard Base64 alphabet.
+   Encode byte string *s* using the standard Base64 alphabet.
 
 
 .. function:: standard_b64decode(s)
 
-   Decode string *s* using the standard Base64 alphabet.
+   Decode byte string *s* using the standard Base64 alphabet.
 
 
 .. function:: urlsafe_b64encode(s)
 
-   Encode string *s* using a URL-safe alphabet, which substitutes ``-`` instead of
+   Encode byte string *s* using a URL-safe alphabet, which substitutes ``-`` instead of
    ``+`` and ``_`` instead of ``/`` in the standard Base64 alphabet.  The result
    can still contain ``=``.
 
 
 .. function:: urlsafe_b64decode(s)
 
-   Decode string *s* using a URL-safe alphabet, which substitutes ``-`` instead of
+   Decode byte string *s* using a URL-safe alphabet, which substitutes ``-`` instead of
    ``+`` and ``_`` instead of ``/`` in the standard Base64 alphabet.
 
 
 .. function:: b32encode(s)
 
-   Encode a string using Base32.  *s* is the string to encode.  The encoded string
+   Encode a byte string using Base32.  *s* is the string to encode.  The encoded string
    is returned.
 
 
 .. function:: b32decode(s, casefold=False, map01=None)
 
-   Decode a Base32 encoded string.
+   Decode a Base32 encoded byte string.
 
    *s* is the string to decode.  Optional *casefold* is a flag specifying whether a
    lowercase alphabet is acceptable as input.  For security purposes, the default
@@ -92,27 +92,27 @@ The modern interface provides:
    digit 0 is always mapped to the letter O).  For security purposes the default is
    ``None``, so that 0 and 1 are not allowed in the input.
 
-   The decoded string is returned.  A :exc:`TypeError` is raised if *s* were
+   The decoded byte string is returned.  A :exc:`TypeError` is raised if *s* were
    incorrectly padded or if there are non-alphabet characters present in the
    string.
 
 
 .. function:: b16encode(s)
 
-   Encode a string using Base16.
+   Encode a byte string using Base16.
 
-   *s* is the string to encode.  The encoded string is returned.
+   *s* is the string to encode.  The encoded byte string is returned.
 
 
 .. function:: b16decode(s, casefold=False)
 
-   Decode a Base16 encoded string.
+   Decode a Base16 encoded byte string.
 
    *s* is the string to decode.  Optional *casefold* is a flag specifying whether a
    lowercase alphabet is acceptable as input.  For security purposes, the default
    is ``False``.
 
-   The decoded string is returned.  A :exc:`TypeError` is raised if *s* were
+   The decoded byte string is returned.  A :exc:`TypeError` is raised if *s* were
    incorrectly padded or if there are non-alphabet characters present in the
    string.