Good morning / Good day.
buon-GIOR-no — the 'gior' sounds like 'jor'. Stress on second syllable.
Say when entering any shop, restaurant, office, or when passing anyone in a small town or building. In Italy, greeting people upon entering is mandatory, not optional. Silence is considered rude.
'Buongiorno' is used from morning until roughly 1–2 pm in most of Italy. After that, 'buon pomeriggio' (good afternoon) or simply 'buona sera' (good evening) takes over. The exact switch point varies by region — in Naples it can be 'buonasera' from noon. Never skip the greeting.
Buonasera.
Good evening.
Used from afternoon onwards — when to switch varies regionally.
Salve.
Hello (formal).
Safe formal greeting usable at any time of day — slightly more distant than 'ciao'.
Ciao.
Hi / Bye (informal).
Only with people you know or who have invited informality. Never to strangers.
In Italian small towns and villages, not saying 'buongiorno' when passing someone on a narrow street is considered startlingly rude. Even in cities, shops expect to be greeted. This greeting culture is one of the first things foreigners notice and Italians notice when foreigners miss it.