The Register reports that Windows 10 will include, defaulted on, "Wi-Fi Sense" which shares wifi passwords with Outlook.com contacts, Skype contacts and, with an opt-in, Facebook friends. This involves Microsoft storing the wifi passwords entered into your laptop which can then be used by any other person suitably connected to you. If you don't want someone's Windows 10 passing on your password, Microsoft has two solutions; only share passwords using their Wi-Fi Sense service, or by adding "_optout" to your SSID.

http://tech.slashdot.org/story/15/07...-with-contacts