diff --git a/README.md b/README.md
index b2e7a55..823364e 100644
--- a/README.md
+++ b/README.md
@@ -19,4 +19,32 @@ it is done with running the SQL command below, and restating the database server
 ALTER SYSTEM SET wal_level = logical;
 ```
 
-## Using the api
+## Project description
+
+The app has these basic concepts:
+
+### User
+
+A user of the system (obviously). User authn is not implemented, authz is very simplified.
+
+### Resource
+
+This is an abstract object representing a project, that multiple users might work on.
+The notion of work on is currently implemented as the comment create action.
+A resource might belong to an organization or belong to the default (null) organization.
+
+### Comment
+
+A text note, that belongs to a given resource, created by a user.
+
+### Region
+
+A geo-located data storage region, currently implemented as a PostgresSQL database server.
+When providing a connection url to a region, make sure to not include a database name or any trailing `/`-s in the url.
+
+### Organization
+
+A collection of users and an owner of resource. Any user may create organizations.
+Organizations may be granted access to any given region. That action creates a new database in the region DB server. migrates it to the latest DB schema and sets up user and resource publish and subscribe mechanisms.
+
+###