diff --git a/book/source/04-certificates.md b/book/source/04-certificates.md
index 5984eef..86cdda2 100644
--- a/book/source/04-certificates.md
+++ b/book/source/04-certificates.md
@@ -82,15 +82,15 @@ Component keys serve in one of two roles: either as an "OpenPGP primary key" or
 
 #### Primary key
 
-The "OpenPGP primary key" is a component key that serves a central role in an OpenPGP certificate:
+The OpenPGP primary key is a distinct component key that serves a central role in an OpenPGP certificate:
 
-- Its fingerprint is used as the unique identifier for the full OpenPGP certificate.
-- It is used for lifecycle operations, such as adding or invalidating subkeys or identities in a certificate.
+- Its fingerprint acts as the unique identifier for the entire OpenPGP certificate.
+- It facilitates lifecycle operations, such as adding or invalidating subkeys or identities within a certificate.
 
 ```{admonition} Terminology
 :class: note
 
-In the RFC, the OpenPGP primary key is also sometimes referred to as "top-level key." It has also sometimes informally been called "master key."
+In the RFC, the OpenPGP primary key is occasionally referred to as "top-level key." Informally, it has also been termed the "master key."
 ```
 
 #### Subkeys