A message thread is a series of replies to a single post. Threads are an intuitive way to organize discussions around a specific topic. Anyone who wants to add their opinion to the initial post can do so by commenting on it, rather than creating an entirely new thread.
Threads are often organized based on the time a comment was added. But they can also be ordered in order of popularity, relevancy, and more.
You can see threads on social media sites, online communities, forums, and message boards