When English speakers meet people they know, they say:
- Good morning / afternoon / evening (formal)
In an informal style, they may say:
- Hello or Hi.
When leaving people, British and American speakers usually say:
- Good morning / afternoon/ evening / night (formal)
In a less formal style they may say:
- Goodbye or Bye.
- Children usually say ‘Bye-bye’.
Other informal leave-taking expressions are:
- See you.
- See you later/tomorrow/next week etc.
- Take care.
- It was nice to meet you.
- Glad to meet you.
- Nice to meet you.
Afternoon starts after lunch and changes to evening after normal working hours.
Evening changes to night at around bed time.
Good evening is used to greet people even at night. It usually has the sense of ‘hello’.
Note that Good night is not used when meeting people; it is used only when leaving people.