A 'finsta' (= fake Instagram) is a secondary Instagram account with a small, trusted audience, where the user posts unfiltered, silly, ugly, embarrassing or vulnerable content they would never post on their main 'rinsta' (real Instagram). If your teen has a finsta, they are using a recognised privacy strategy — but it is worth knowing what is on it, particularly because finstas have been involved in mental-health crises and bullying incidents. Calm conversation about who follows it is appropriate.