diff --git a/book/source/glossary.md b/book/source/glossary.md
index a2eb895..7f75c07 100644
--- a/book/source/glossary.md
+++ b/book/source/glossary.md
@@ -157,7 +157,9 @@ Detached Signature
     A {term}`Data Signature` which exists separately to the data it was created for. See [](forms-of-data-signatures).
 
 Direct Key Signature
-    A {term}`Signature` that sets preferences and advertises {term}`features<Features Subpacket>` applicable to an entire {term}`Certificate`. See [](direct-key-signature).
+    Describes both a {term}`Signature Type ID`, as well as an according {term}`OpenPGP Signature` over a {term}`Primary Key`.
+
+    Issued as a {term}`Self-Signature` it sets preferences and advertises {term}`features<Features Subpacket>` applicable to an entire {term}`Certificate`. See [](direct-key-signature).
 
 Embedded Signature Subpacket
     An {term}`OpenPGP Signature Subpacket` which contains a complete {term}`OpenPGP Signature Packet`.