Navgar's Chat module is the connective tissue between you and the rest of your team across Tasks, Groups and Flows that allows for informal communication. Chat allows you to add and read comments on tasks, project tasks, flows, and in ad hoc form (one on one/group). Chat can also be used to leave comments and reminders on tasks that are assigned to you to keep others involved in the conversation informed.
Chats help you and your team with ad-hoc/unstructured communication around the goal you are trying to accomplish. For example, while a Flow is a highly structured series of predetermined tasks, Chat allows for follow up conversation or questions that while not formalized are important for moving the Flow forward.
There is even a Flow Template chat, allowing the creator and participants to maintain visibility and context to changes to the Flow Template itself.