Windows XP/2000 implements automatic login (in the case of adding a domain or not adding a domain)

Windows XP/2000 enables automatic login:
You can change the registry regardless of whether the computer has added a domain.
Create several key values in the Registry HKEY_LOCAL_MACHINE/software/Microsoft/Windows NT/current version/Winlogon.
Create a two-byte (REG_DWORD) value item AutoAdminLogon. If the value is 1, the automatic logon function is enabled. If the value is 0 or the value does not exist, the automatic logon function is not used.
Modify the value of the defaultdomainname string to the default domain name (local name or localhost ). If the machine is not in the domain, the value of this value item is the name of the computer.
Modify the DefaultUserName value of the string value item to the default user name.
Modify the defaultpassword value of the string value item to the default password. If the password is empty, delete the item. If not, add it.
After the instance is restarted, the new settings take effect.
(In addition, some people say that you can choose to log on automatically when installing the Windows 2000 operating system, so that you can log on automatically when installing the system without setting it. I am not sure yet)

A simpler method for systems not added to a domain:
Windows XP/2000 requires you to select an account and enter a password each time you start the system. This is safer for a public computer, however, it would be too difficult to select an account and enter a password for this computer. How can I enable Windows XP to automatically log on without entering a password?

Click Start/run and enter rundll32 netplwiz. DLL, usersrundll, press enter to bring up the "User Account" window, deselect the "to use the local machine, the user must enter the user name and password" option, click OK, in the displayed dialog box, enter the account and password that you want your computer to automatically log on.

The following is a part of the Windows Help document. From this document, we can see that the above method is not feasible when the computer is added to the domain.

To require or disable a logon password in workgroup settings:
Open "user and password" in "Control Panel"
On the users tab, perform any of the following operations:
Click the "user must enter the user name and password to use this computer" check box. This information is required for logon.
Clear the check box "users must enter the user name and password to use this computer" to allow users to log on automatically. The system prompts you to enter the username and password of the user who automatically logs on to the machine each time.
Note:
The "user must enter the user name and password to use this computer" check box appears only when your computer is not connected to a network domain.
You must log on as administrator or a member of the Administrators Group to use the "user and password ".
If only one user is using the computer or the security risk is low, it is very convenient to enable Windows 2000 to log on automatically every time it is started.