When considering the context of online communication, what does it mean to say that communication has a synchronous temporal structure?

Communication has a synchronous temporal structure

Explanation:

Temporal Structure communication means a communication can be synchronous or asynchronous. Real-time communication is a synchronous type. It is usually face to face or phone calls, or instant messages as these all occur in real time.

If messages have delay between them, it is a asynchronous type of communication, like an email or voice mail. Thus, online communication has temporal structure communication can be both synchronous or asynchronous as it can be real time in case the chats are instant online and in case of emails, it is asynchronous.