Text Channels
Text channels provides a chatroom that’s typically oriented around a specific topic. Users in the text channel can send, receive, and interact with messages. Text channels are the primary means of communication and are the default channel type.
Replies
Replies allow a user to reference a prior message in a text channel when sending a new message. The referenced message is typically displayed as a small quote above the new message, along with a link to navigate to that old message in scollback.
Reactions
Reactions allow users to “react” to a message in a text channel using an emoji. These emojis can either be the standard unicode emojis, or custom emojis defined by the server. See more about server emojis on their documentation page.