Who are the thought police?

It's pretty
much what it sounds like. In their society they have police to monitor all your actions; they
also have special "police" to monitor your thoughts.  This is possible because you can
commit "thought crime" in their society.  Their task is to go beyond hunting down
criminal acts and instead hunt out criminal thoughts, which are any thoughts that go against
those approved by the state.  For example, it is a crime to stand up and shout, "Down with
Big Brother," and in their society, it is also a crime to even think it.  

This view that thought can be a crime is shared by many totalitarian societies; Stalin
is thought to have had 20 million of his own people killed, many of them on suspicion of
thoughts against the state.  It's pretty easy to control people if they know their neighbor
disappeared last night for what he/she thought.

Parsons is a good example in
the book (although he is almost comic).  He is turned in by his children
for thought crime and thanks them for it because, as he says, he wasn't even
aware that he was committing thought crime.

Pretty
scary...