AD is the abbreviation of Latin Anno Domini, which means AD. In the Gregorian calendar, we use the year AD to represent a specific date and time. Good night followed by AD means to express the end of today and the expectation of tomorrow.

In modern society, it is more of a courtesy and habit to add ad after saying good night. In the workplace or formal occasions, people will say good night at the end of the evening, and add AD to remind everyone of tomorrow's work or schedule, so as to get ready.

Good night followed by advertisements is usually used in formal business and workplace. For example, when you end a meeting or phone call with a customer or colleague, say good night and add advertisements to show mutual understanding and respect.

In addition, in some more formal and traditional occasions, people will also use the form of good night followed by advertisements. For example, in the tutoring activities between teachers and students, the teacher will say good night and AD at the end of the evening tutoring, so that students can remember to review and prepare for class tomorrow.

Advertising after good night is becoming more and more important in modern social etiquette. This is not only a courtesy, but also a way of respect and care.

In modern society, everyone's pace of work and life is very busy. The form of adding AD after good night can remind everyone of tomorrow's schedule and plan, and also allow people to better plan and arrange their own time. At the same time, adding ad after good night can also express respect and recognition for interpersonal communication and social system, and make others more willing to communicate and cooperate with you.