If your website is at least just a bit popular you'll get a lot of spam in form of comment spam for example but also as registration spam: spambots will try to sign up on your site and fill your database with garbage. The Orchard registration page is no different: but now you can use Orchard's spam countermeasures there as well with the Lombiq Antispam module. We added a new feature to this module that lets you add anti-spam content parts from the built-in Orchard.AntiSpam module to the registration page as an additional layer of validation: when anti-spam validation fails, registration will fail. You can read about the details in the documentation of the module (accessible from its project page) and you can also see it action on the Orchard Community Meeting.