Why do I get electrostatic shock due to wool, but not due to cotton? I have experienced electrostatic shock quite a lot of times because of a woollen fiber, and as far as I can remember, never due to a cotton fiber.
Any explanation as to why this happens?
Edit:
I understand why we get static shocks, but I want to ask why we get static shocks with wool but not with cotton? I mean why doesn't cotton get electrostatically charged?
 A: Triboelectric properties of cotton are irrelevant because it is more important that cotton is a fairly good conductor for discharging static electricity, it is not an insulator like wool. This can be easily demonstrated with an electroscope. A charged electroscope quickly (i.e., within a second) discharges through a piece of cotton. In contrast, the electroscope does not discharge through a piece of wool. Presumably wool is a good electric insulator because wool fibres have a waxy coating.   
A: When you rub two dissimilar materials together, it's possible for charges to get pulled off of the surface of one material and onto the surface of the other. This is the reason you get "static shocks" like what you experienced. 
How much charge gets transferred and which way it moves depends in a complicated way on exactly what the two materials are made from and also on things like how dry the air is that surrounds the objects being rubbed. 
There's practically no way to predict in advance which materials (cotton, wool, silk, nylon, etc.) you rub against other materials (amber, hard rubber, glass, plastic, etc.) will result in charge transfer from one to the other. 
For more detailed information, I'd take  user1936752's advice and look up triboelectricity. 
