In and out points can be used to create subclips. To create a subclip once you have your in and out points marked on your keyboard press the letter S. This will create a subclip. Pressing S twice will bring up the subclip name and description menu. You can see that length of the clip is based on the in and out points you had chosen prior to creating that subclip.
You can create various subclips from the same media and they will all show up on the right portion of the player under the subclips tab
You can also play, edit, delete, export, seek an in point or out point of a specific subclip by right-clicking over the subclip in the subclip tab.