Replying to someone and not sure who else will see it? Here’s how it works….
An @reply only appears in the timeline of those who are following both users in the conversation. So if I was replying to a tweet by Duncan Bannatyne, it would only appear in the timeline of people following me who are also following DB. Comprende?!!
BUT!!! It will be visible on your profile and in searches. So it is very much in the public domain.
So, if you want a private conversation do it via direct message!!