What is an "agitator?"

Now, you know the thing inside your upright washing machine? That pole-like thing sits in the middle to rotate back and forth and get your clothes clean. That is an agitator. But, that really doesn't answer the question.

Let's turn to the dictionary:

agitate -
1 a obsolete : to give motion to
b : to move with an irregular, rapid, or violent action
the storm agitated the sea
2 : to excite and often trouble the mind or feelings of : DISTURB
3 a : to discuss excitedly and earnestly
b : to stir up public discussion of
intransitive senses : to attempt to arouse public feeling

agitator -
one that agitates : as
a : one who stirs up public feeling on controversial issues
political agitators
b : a device or an apparatus for stirring or shaking

source: m-w.com

I would apply all of the above to this humble blog.