Attempt to document AES
diff --git a/docs/primitives/symmetric-encryption.rst b/docs/primitives/symmetric-encryption.rst
index 7081e01..750ab88 100644
--- a/docs/primitives/symmetric-encryption.rst
+++ b/docs/primitives/symmetric-encryption.rst
@@ -32,8 +32,14 @@
Ciphers
~~~~~~~
-AES
-+++
+.. class:: cryptography.primitives.aes.AES(key)
+
+ AES (Advanced encryption standard) is a block cipher standardized by NIST.
+ AES is both fast, and cryptographically strong. It is a good default
+ choice for encryption.
+
+ :param bytes key: The secret key, either ``128``, ``192``, or ``256`` bits.
+
Modes
~~~~~