Your pinned message board acts as a virtual bulletin board for your channel. You can "pin" important messages or attachments for convenient access for the whole group.
What is "Pinning" a message
Pinning a message is a great way to store a selected message in a separate space so everyone in the chat can reference it later on. Check pinned messages by clicking on "Pinned Messages" under your channel menu, which can be found by clicking the three dots in the upper right-hand corner.
How to pin a message on your channel:
Hover cursor over the message you wish to pin.
Towards the right side of the highlighted message, you should see three dots.
Click the three dots to reveal the dropdown menu.
Your message can now be found on the "Pinned Messages" board.
To view pinned messages:
Open the channel you wish to view the pinned messages on.
Click on the vertical three dots at the top right corner of your channel.
Select "Pinned Messages" on the dropdown menu that appears.
Read pinned messages in the sidebar or select "Jump to Message" to read it in the main chat.