Users can subscribe to be notified of all new posts that occur within categories of the forum. This way you can quickly answer questions that pop up about topics that you are knowledgeable about. For example, if I am an expert coder, I could subscribe to the ViDA Questions > Coding category, so I can be notified by email as soon as a question comes up, and answer it immediately.
To do this, navigate to the category that you wish to subscribe to and click the circle icon in the top right. Then select the level at which you wish to subscribe at. For this example, you probably want to select “Watching First Post” so that you are notified of new posts, but not every time that someone replies to an existing one.