In summary
A content note is a verbal or written notice that precedes potentially sensitive content. They flag content which may be distressing - to anyone, particularly those with related experiences - and/or triggering to those with PTSD or similar mental health conditions.
Content notes allow people the opportunity to prepare themselves, in an informed way, to engage with a given piece of material.
Content notes are sometimes referred to as 'trigger warnings' or 'content warnings'; this guide uses 'content notes' as a more neutral, descriptive term.