dumb fan question time....gather around

[deanbw]

I have a guy, no,no a friend, no wait...a friend of my brother, a guy I once knew....anyway, it's not me, I would never ask this.
I, (he,them) have a fan question, mine (dang it now you know) has a small resistor? relay? on the back of the motor, no biggie but I see some don't. Does anyone know what the little bugger is for and way some have it and some don't?
here is a couple pics I found online that show one with, one without
Thanks

[virgilmobile]

It should be a filter capacitor.

[deanbw]

It should be a filter capacitor.

thank you, makes sense, keep the electrics clean...