By default (using business accounts) Pardot creates new records as:
Leads
Contacts
Which scenario would convert an anonymous visitor into an identified prospect?
Creating a Lead in Salesforce which syncs to Pardot as a new prospect record
Scanning the badge of someone who visited a booth at a recent event
Submitting a Web2Lead form that is linked to Pardot via a form handler
Opening email sent by a sales rep using the Send Pardot Email functionality in Salesforce