An “itch” is also known as pruritus. This is a general sensation that can occur anywhere on the skin - it’s basically an irritation of skin cells or nerve cells.
Itches can be annoying, but they are also an important component of our sensory system. The itching feeling is a self-protective mechanism, as it sends a signal to the brain that something is amiss with that area of skin.
When we scratch an itch, we suppress the feeling by creating pain (albeit a tiny amount). Depending on the cause of the itch, scratching can satisfy the itching sensation permanently. However, in some cases it only suppresses the feeling temporarily, and the itch returns.
