diff --git a/docs/CARD_PRIVACY.md b/docs/CARD_PRIVACY.md
index 9178b6f..6d6af6d 100644
--- a/docs/CARD_PRIVACY.md
+++ b/docs/CARD_PRIVACY.md
@@ -1,6 +1,10 @@
 # Card Privacy
 
-## Brief
+## Payment tracking
+
+This document describes the different levels of privacy possible with bolt card implementations.
+
+## Card NDEF
 
 The URI that is programmed into the card and returned as the NDEF consists of three parts.
 1. The static part
@@ -23,7 +27,32 @@ lnurlw://card.yourdomain.com/ln?p=                                &c=
 | encrypted | unique id and counter values encrypted by the card |
 | authentication | a value to authenticate that the entire URI is as generated by the card |
 
-## NXP NTAG424DNA features
+## Card privacy levels
 
-## Implementation
+In order for the system to work, the card must provide the point-of-sale with a URL for the backend server.
+For maximum privacy, it should not be possible for the point-of-sale to identify the card any further than this.
 
+Unfortunately, early implementations do not have this fully built out.
+
+You can check your card/s by reading the NDEF value (e.g. with the NXP TagInfo app) to check for a static identifier or a static UID value. This will enable you to find the level of privacy that has been implemented on creating the card.
+
+### Minimal privacy (aka tracker)
+
+An identifier is included in the static part of the lnurlw.
+This is used on the server side to look up the decryption key and the authentication key per card.
+This is how early systems were implemented and allows the point-of-sale devices to track the use of the card.
+
+### Good privacy
+
+There is no identifier included in the static part of the lnurlw.
+This is made possible by holding the decryption key at database level.
+The authentication key is still recorded per card.
+
+This protects against leaking of point-of-sale databases and log files, however, a untrustworthy point-of-sale could still obtain the card UID using proprietary NXP commands.
+
+### Best privacy
+
+There is no identifier included in the static part of the lnurlw.
+In addition, the UID field is made inaccessible by NXP proprietary commands by using the Random ID feature.
+
+This protects against individual card tracking by trustworthy and untrustworthy point-of-sale systems.