How does "focus" and "defocus" change the forum view?

[csouth154]

Perhaps this is a bit "derp"-y, but I can't figure this out. It's clearly a filter...I just can't figure out exactly what is being filtered.

[Joana]

When you select "Focus" view, you only see threads that you've posted in and threads you've read which have new posts. "Defocus" takes you back to all threads.

[Hawkmoon269]

What is focus?
What are the dots?