diff --git a/docs/glossary.rst b/docs/glossary.rst
index ce08dba..95b893c 100644
--- a/docs/glossary.rst
+++ b/docs/glossary.rst
@@ -94,6 +94,11 @@
         bit key, you can calculate the number of bytes by dividing by 8. 128
         divided by 8 is 16, so a 128 bit key is a 16 byte key.
 
+    bytes-like
+        A bytes-like object contains binary data and supports the
+        `buffer protocol`_. This includes ``bytes``, ``bytearray``, and
+        ``memoryview`` objects.
+
     U-label
         The presentational unicode form of an internationalized domain
         name. U-labels use unicode characters outside the ASCII range and
@@ -101,3 +106,4 @@
 
 .. _`hardware security module`: https://en.wikipedia.org/wiki/Hardware_security_module
 .. _`idna`: https://pypi.org/project/idna/
+.. _`buffer protocol`: https://docs.python.org/3/c-api/buffer.html