It's called a "Hardware Interrupt". Meaning it makes it harder for someone to use something other than a password to get on. I can't think of a time where it would matter off hand but it is early. I'll check my book later or something unless someone else replies and gives an example instead. I think it was something with being able to use a program to get things at log in....I forgot, I've never really looked into it much but had to do some readin on it for my Security + So I'll check later on.