A simple explination
When you leave a note, this site stores your name, your message, and a scrambled ("hashed") version of your IP address. It's used for one thing only: stopping spam and repeat abuse. It's never shown publicly, sold, or used for anything else.
Let's be honest, are you comfortable with anyone having your full IP?
A hash is a one-way scrambling process. Your IP goes in, a fixed-length jumble of letters and numbers and symbols which the site owner (me) created by repeatedly mashing my keyboard, and then it bakes out a hashed ip.
Imagine your IP as a steak. You just finished cooking it. Taste it without the salt, your gonna spit it out (i dont want my ip given to anyone). Now, add "the salt", Tastes pretty good now, right? (no IP given to anyone, the hashed ip is unreversible) Everyones happy! I can stop fraud without you worrying about your IP being leaked
Nobody see's your IP. You can rest easy now.