That web site does not render properly in Chrome and Brave browsers, as the page doesn't scroll or respond to inputs. Only in Firefox can I highlight the text to scroll by highlighting, then copy to a text editor to read. There is a WebSocket connection error and uncaught exceptions in the debug console.

Ok, was able to read. Thank you. Event kind identifies a type of data for a use case. NIP-31 gives an alt tag so apps seeing an unrecognized kind can still display a text description for context. NIP-89 lets users discover microapps from other Nostr users for handling a kind, so that we can have a free market for microapps instead of being vulnerable to centralized control by an app store. This also decentralizes control by verticalized silos that tie data to apps. Brilliant.