I plan to purchase a floor mat for my computer chair to roll on instead of having it directly on the carpet soon. I see that a lot of them are advertised as anti-static, such as this one. These products' descriptions usually claim that having such an anti-static floor mat under your computer chair will protect your computer from damage caused by electro-static discharge. I'm pretty familiar with the hazards of static electricity to computers, but I'd never heard of static damage caused by the user sitting on the chair. I thought this sort of damage was only a concern when one is working on the inside of a computer, and that it wouldn't affect the computer from the outside. It seems strange that they act as if static electricity could affect my computer when I'm sitting at the desk; does it supposedly go though the keyboard or something? If this could actually harm my computer, it's news to me, but I can't find any information on the necessity of these chair mats except advertisements for them. Would someone explain how this is necessary or unnecessary?