same origin policy---local file and remote files

Internet browsers run scripts locally in order to speed up processes that might normally take longer amounts of time due to ... scripts running remotely (from another machine in istant cyberspace). "Same origin policy" is a programming adherent's use of constraining running of scripts to usually one or the other. The reason, as stated in wiki, is that there are security bugs and they're most plentiful in the realm of the local breach. IOW: don't put passwords, usernames, or cookies anywhere near each other.