This scope lets an app "View messages and other content in public channels that your slack app has been added to"
This OAuth permission scope works with these Web API methods and Events API events.
channels.history - Fetches history of messages and events from a channel.channels.replies - Retrieve a thread of messages posted to a channelchannel_history_changed - Bulk updates were made to a channel's historymessage - A message was sent to a channelmessage.channels - A message was posted to a channel