diff --git a/content/en/client/intro.md b/content/en/client/intro.md
index e3d98abd..2f14aad2 100644
--- a/content/en/client/intro.md
+++ b/content/en/client/intro.md
@@ -64,6 +64,8 @@ curl -X POST \
 
 ### JSON {#json}
 
+*JavaScript Object Notation* as defined in ECMA-404. Quick one page overview: https://www.json.org/
+
 Similar to sending form data, but with an additional header to specify that the data is in JSON format. To send a JSON request with cURL, specify the JSON content type with a header, then send the JSON data as form data:
 
 ```bash