Is a note considered as an interaction?

Yes, any communication that is visible to the requester is considered an interaction. 

Let's say an agent is working on a ticket and adds a public note to the ticket, requesting additional information from the requester. When the requester responds to the agent's note, that response is also considered an interaction.

Thus, any communication that is visible to the requester, whether it's an agent's public note or a response from the requester, is considered an interaction in Freshservice.
This helps in tracking the communication history between the requester and the agent and provides a clear record of all the interactions that have taken place in a ticket.