Best kept to a computer only you use
Automatic login is convenient specifically because it removes a barrier that exists to protect your account, which means anyone who can physically turn on that computer can get straight into your account and files. It's best reserved for a personal device in a space you already control, not a shared family computer or one anyone else has physical access to.
It doesn't remove password protection everywhere
This setting only skips the sign-in screen for that one local account; it doesn't affect passwords required elsewhere, such as an online account you sign into separately inside a browser or app. If the device is ever lost or stolen, anything still protected by its own separate password remains safe even though Windows itself will boot straight to the desktop.
Frequently Asked Questions
Should I set this up on a computer other people also use?
It isn't recommended. Once enabled, anyone who turns the computer on can get straight into your account without a password, which weakens security.
How do I turn automatic login back off?
Run "netplwiz" the same way, re-check the checkbox, and apply the change -- the login screen will ask for a password again like before.