Sends a confirmation request email to a user when they sign up for a new user account (without signing up for a site at the same time). The…

Update the last_updated field for the current site.

Processes new site registrations.

Sanitizes and validates data required for a user sign-up.

Notifies the site administrator that their site activation was successful.

Notifies a user that their account activation has been successful.

Fires after a network site is activated.

Fires immediately after a user is added to a site.

Fires immediately after an existing user is added to a site.

Fires after the Multisite DB upgrade for each site is complete.