Every channel in every Team starts with a Posts tab. Think of this tab as a message board for all members of the channel. Posts are visible messages to all members of the channel and are structured as threaded conversations pertaining to the focus of the channel. 

When making a post, you will find an assortment of buttons beneath the conversation text box. These buttons provide options to format the text, attach files, add emojis, GIFs, and stickers, and more. Learn how to post a message to a channel.