Windows 10 has a feature called Wi-Fi Sense that makes it easier for friends and family to get on your encrypted Wi-Fi networks. They do not have to type a password; Microsoft will log them in automatically WITHOUT giving anyone your Wi-Fi password. You have a lot of control over how it works, and you can even disable it completely.

For example, someone only gets logged in automatically if she/he is a contact of yours in Outlook, Outlook.com/Hotmail, Skype, or Facebook. If you remove someone from your contacts, she/he cannot connect.

You can also choose which of the above services to pull contacts from by performing the procedure below:
  • Go to Network & Internet>>Wi-Fi>>Manage Wi-Fi Settings (only available on computers that support Wi-Fi).
  • Uncheck the services you do not want to allow under "For networks I select, share them with my contacts."
You might have noticed it says "for networks I select." The first time you connect to a Wi-Fi network, Microsoft will ask if you want to share it. Simply say no and Wi-Fi Sense will not log anyone in to that network. You can also disable these later in your network settings.