feat: add uses cases for nip-27

1 files changed, 16 insertions, 0 deletions

diff --git a/27.md b/27.md
index d8a236e..2a0663e 100644
--- a/27.md
+++ b/27.md
@@ -66,3 +66,19 @@ up to date. Both would construct the following message to subscribe:
   }
 ]
 ```
+
+# Use Cases
+
+1. Subreddit/IRC-like channels (e.g. `{ "#m": ["#newbies", "r/nostr", "#mp3s", "r/oldschoolcool"] }`) over Nostr.
+1. Forums over Nostr. (e.g. `{ "#m": ["itguys.com/IT/Support/Hardware", "itguys.com/General/Announcements", "itguys.com/General/New Users", "itguys.com/Social/Memes"] }`)
+1. Clients wishing to filter out all the noise from public events may choose to only subscribe to multicast groups. Apps/games/bots leveraging Nostr may prefer communicating over a multicast group to avoid collision with the broader public.
+1. A hard-to-guess multicast group can be used for increased (but not total) privacy over a trusted relay. A "channel-hopping" algorithm shared by clients may improve privacy in this scenario where a channel is a multicast group.
+1. Two or more parties may initiate contact publicly using Direct Messaging and agree privately on a hard-to-guess multicast group before continuing their exchange hiding further metadata from being leaked to the public. Parties can re-negotiate a new hard-to-guess multicast group at any point.
+1. Live events can take advantage of ephemeral events and previously-shared multicast group for communication during the event.
+1. Smart contracts may communicate in privacy-preserving way with individual clients using unique short-lived multicast groups.
+1. Clients interested in Bitcoin prices in USD may subscribe to the multicast group "prices:btc:usd". Many providers may publish their events to the same multicast groups.
+
+# Notes
+
+1. Events sent to multicast groups should be considered public, after all they are readable by relays and can also be reshared by any client subscribed to the multicast group.
+1. Multicast groups are not a replacement for encrypted direct messages but can work in conjunction.