Thanks for the responses and the info in them. I am unsure if my query has been explained well enough. By using the term "hot topic", I fear that I have caused confusion.
From the home page, I click on "Show unread posts since last visit". I get a list of threads which shows title, originator, no. of replies and last member posting. If there are two threads each with 20 replies, I cannot tell which one of these was posted yesterday and which one was started 3 months ago. In such a case, I would prefer to read the thread which was posted yesterday.