diff --git a/edn.html.markdown b/edn.html.markdown
index 79107269..04346eb8 100644
--- a/edn.html.markdown
+++ b/edn.html.markdown
@@ -3,13 +3,16 @@ language: edn
 filename: learnedn.edn
 contributors:
   - ["Jason Yeo", "https://github.com/jsyeo"]
+  - ["Jonathan D Johnston", "https://github.com/jdjohnston"]
 ---
 
 Extensible Data Notation (EDN) is a format for serializing data.
 
-The notation is used internally by Clojure to represent programs. It is also
-used as a data transfer format like JSON. Though it is more commonly used in
-Clojure, there are implementations of EDN for many other languages.
+EDN is a subset of the syntax used by Clojure. Reading data defined by EDN is
+safer than that defined by the full Clojure syntax, especially from untrusted
+sources. EDN is restricted to data, no code. It is similar in intent to JSON.
+Though it is more commonly used in Clojure, there are implementations of EDN
+for many other languages.
 
 The main benefit of EDN over JSON and YAML is that it is extensible. We
 will see how it is extended later on.