Add introduction (#246)

* Add introduction

* Consolidate abstract and introduction

* Split abstract and intro again

Author: mickenordin

IETF-RFC.md

@@ -36,18 +36,44 @@ author:
     uri: https://code.smolnet.org/micke
 
 --- abstract
+Open Cloud Mesh (OCM) is a server federation protocol that is used to
+notify a Receiving Party that they have been granted access to some
+Resource. It has similarities with authorization flows such as OAuth,
+as well as with social internet protocols such as ActivityPub and email.
 
-Open Cloud Mesh is a server federation protocol that is used to notify a
-Receiving Party that they have been granted access to some Resource.  It
-has similarities with authorization flows such as OAuth, as well as with
-social internet protocols such as ActivityPub and email.
+A core use case of OCM is when a user (e.g., Alice on System A) wishes
+to share a resource (e.g., a file) with another user (e.g., Bob on
+System B) without transferring the resource itself or requiring Bob to
+log in to System A.
+
+While this scenario is illustrative, OCM is designed to support a
+broader range of interactions, including but not limited to file
+transfers.
 
 Open Cloud Mesh only handles the necessary interactions up to the point
 where the Receiving Party is informed that they were granted access to
 the Resource.  The actual resource access is then left to protocols such
 as WebDAV and others.
 
 --- middle
+# Introduction
+
+Open Cloud Mesh was initially conceived of in 2015 and has been deployed
+since 2016. OCM has been implemented by several platforms, including
+CERNBox, Nextcloud, OpenCloud, ownCloud, and Seafile.
+
+The goal of OCM is to provide a secure, scalable, and flexible
+infrastructure for securely sharing and collaborating on resources and
+has seen wide adoption, not least in the academic sector.
+
+The core idea of OCM is to make it simple for users to do the right
+thing. This is achieved by providing a protocol that abstracts away
+security and authentication details from the users to the servers acting
+on behalf of the users. Another important point of the protocol is the
+invitation mechanism that lets users connect over established human
+relationships and uses those connections to establish contact between
+their respective OCM servers.
+
 
 # Terms
 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL