In formal Italian, what are the appropriate forms of address for someone you don't know but need to show respect to?

In formal Italian, the appropriate form of address for someone you don't know but need to show respect to is 'Lei'. 'Lei' is the formal singular 'you' and requires verbs to be conjugated in the third-person singular. When addressing someone formally, it's crucial to use 'Lei' consistently, avoiding mixing it with the informal 'tu' (informal 'you'). In written communication, 'Lei' is typically capitalized to further emphasize formality. Additionally, it's polite to use professional titles when addressing someone. For example, if you know someone is a doctor, you would address them as 'Dottore' or 'Dottoressa' (if female), followed by their last name if known. So, you might say 'Buongiorno, Dottor Rossi' (Good morning, Dr. Rossi). If their professional title is unknown, 'Signore' (Mr.) or 'Signora' (Mrs.) followed by their last name are appropriate. Therefore, combining 'Lei' with professional titles or 'Signore/Signora' demonstrates appropriate respect in formal Italian interactions.