When you sign out of Windows, all of the applications that you were using are closed, but the PC isn't turned off. Another person can sign in without needing to restart the PC – but even if someone else turns off the PC, your information won't be lost.
You also don't necessarily have to sign out of Windows. You can lock the PC instead, and other people can still sign in to their accounts from the sign-in screen.
"Sign in to" and "sign out of" mean the same as "log on to" and "log out from", respectively.
Open Start by swiping in from the right edge of the screen (or if you're using a mouse, pointing to the top-right corner of the screen and moving the mouse pointer down), then tapping or clicking Start.
Tap or click your account picture in the upper-right corner, and then choose Sign out.
Swipe up from the bottom edge of the screen (or press any key if you're using a keyboard) to dismiss the lock screen.
In the sign-in screen, sign in to your PC using the method of your choice.
If you want to sign in with a different account than the one shown on the sign-in screen, tap or click the Back button and choose an account. If you're prompted to press Ctrl+Alt+Delete, do so.
To pick a different sign-in method, tap or click Sign-in options to see the available choices.
You can also switch to a different user account without signing out of Windows.
Tap or click your account picture in the upper-right corner, and then do one of the following:
If you see the user account you want to sign in with, tap or click that account.
If you don't see the account you want to use, tap or click Switch accounts. You can then sign in with an existing account or create a new one.