After installing fresh new Joomla and configuring Global Settings, the next important step is to configure user manager options. Again, this will depend upon your website requirements. Do you want to enable registration and login functionality (restricted content visible to only those who are registered with your site)?
Login to your Joomla Backend and go to User Manager. Then click on Options (top right side before help).
Allow User Registration: If you require register and login, then select yes. Otherwise select No and you can ignore all other options.
New User Account Activation: This option is used to verify the email address or admin control over registered users.
None. User account will be active immediately with no action required.
Self. User will receive an email with an activation link. The account will be activated when the user clicks the activation link.
Admin. User will receive an email with an activation link. When the user clicks this link, the Site Admin will be notified via email and the Site Admin needs to activate the user's account.
Notification Mail to Administrators: Do admins be notified whenever someone registers?
Captcha is used to stop spam registrations in Joomla.