diff --git a/Database.md b/Database.md
index 2f5869c..b291494 100644
--- a/Database.md
+++ b/Database.md
@@ -11,9 +11,21 @@ The database model used by TETHYS is based on a relational database model. The m
 * File Table: This table stores information about the files that are associated with the resources in the system. Each file is assigned a unique identifier, and the table includes fields for the file name, file type, and other metadata.
 
 The database model used by TETHYS is designed to be flexible and extensible, allowing for the addition of new tables and fields as needed to support different types of digital resources.
-### 
-### TETHYS ACL Tables
-### 
+
+
+# TETHYS ACL Tables
+# 
 ![title](./tethys_acl.png)
 
+TETHYS provides an Access Control List (ACL) system that is used to manage users, user roles and permissions.
+
+## The ACL tables used by TETHYS are:
+
+roles: This table stores information about the roles that are available in your application. Each role has a unique identifier and a name that describes the role.
+
+permissions: This table stores information about the permissions that are available in your application. Each permission has a unique identifier, a name that describes the permission, and a short code that represents the permission.
+
+role_has_permissions: This table stores the relationship between roles and permissions. Each row in this table represents a role that has been granted a specific permission.
+
+link_account_roles: This table stores the relationship between users (Accounts) and roles. Each row in this table represents a user that has been assigned a specific role.