diff --git a/book/source/04-certificates.md b/book/source/04-certificates.md
index 597704c..2d856d2 100644
--- a/book/source/04-certificates.md
+++ b/book/source/04-certificates.md
@@ -3,9 +3,9 @@
 
 OpenPGP fundamentally hinges on the concept of "OpenPGP certificates," often referred to as "OpenPGP keys." These certificates are complex data structures essential for identity verification and data encryption. Understanding their structure and functionality is pivotal for effective application of the OpenPGP standard.
 
-## Terminology: The various meanings of "key"
+## Terminology: Understanding "keys"
 
-The concept of "(cryptographic) keys" plays a central role, when looking at OpenPGP certificates. Confusingly, the term can be used to refer to a number of subtly different things.
+The term "(cryptographic) keys" is central to grasping the concept of OpenPGP certificates. However, it can refer to different entities, making it a potentially confusing term. Let's clarify those differences.
 
 ### Private vs. public keys