Often a comment needs to be seen by your team only, private from the client. Add internal notes to conversations and discuss posts behind the scenes with your internal team only. Internal notes are marked with a yellow-ish color. 

You can create an internal note only if you have a user assigned as a client in your workspace - it will allow you to create both internal notes and internal posts (find out more)

Learn how to assign a user as a team member or client.