session docs

docs/README.md

@@ -24,3 +24,4 @@ Installation guide for developers (technical):
 - [Updating the kit to the latest version](updating-the-kit.md)
 - [Tips and tricks](tips-and-tricks.md)
 - [Creating routes (server-side programming)](creating-routes.md)
+- [Storing data in session](session.md)

docs/session.md

@@ -0,0 +1,23 @@
+# Storing data in session
+
+**Advanced topic**
+
+If you need to store data for each user, the best way to do it is using session data.
+
+This means that if more than one person is using your prototype, their data will not get mixed up.
+
+The easiest way to clear session data is to use 'Incognito mode' for each user, and close that window when you're done.
+
+## How to use
+
+In a route function, refer to `req.session`.
+
+For example you might have `req.session.over18` or `req.session.firstName`.
+
+You can see a full example here:
+
+[https://github.com/expressjs/session#example](https://github.com/expressjs/session#example)
+
+You can read more about Express Session here:
+
+[https://github.com/expressjs/session](https://github.com/expressjs/session)