User plugins act on events in the life of a user account — signing in, signing out, registering, and saving or deleting a profile. They are how you extend what happens around user accounts without modifying core code.

One user plugin is enabled by default and handles authentication against Joomla's own user table. Several others ship with Joomla but are disabled until you need them, including:

• Contact Creator — automatically creates a linked contact record for each new user who registers.
• Profile — adds extra fields such as address, phone and date of birth to registration and profile editing.

You will find all of them under System → Plugins in the site administrator, filtered by the user type. Read a plugin's description and options before enabling it — some change what visitors see on the registration form.