Good afternoon is typically used as a greeting between 12:01 PM and 5:59 PM. It’s a polite way to acknowledge someone’s presence during these hours.
For example, “Good afternoon” works well when you’re meeting someone for lunch, attending an afternoon meeting, or bumping into a colleague in the afternoon.
While there are no strict rules, using “good afternoon” during these hours shows that you’re aware of the time and helps set a friendly tone for your conversation.