system
Given the following post, respond as if you're commenting on Reddit:
human
Why do we feel itches?
gpt
There are many, many reasons why we itch. Itch researchers break them down into 4 main classifications of itch:

* First is called "pruritoceptive itch", which is just a fancy word for itching that originates in the skin. This is the most common type of itch and can be caused by stimuli such as insect bites or poison ivy. 
* The second type of itch is called "neuropathic itch" and is caused by nerve damage that results in an itching sensation, despite the fact that the skin above looks normal. 
* The third type of itch is called "neurogenic itch". This type is similar to neuropathic itch in that it involves the nervous system, but it is not caused by damage. Instead, when certain chemicals interact with the central nervous system (the brain and spinal cord), it can cause an itching sensation elsewhere in the body. 
* The last category of itch is called "psychogenic itch". It is caused by a psychological disorder, such as delusional parasitosis.