For questions about the web interface of Google's people manager, either as a standalone product or associated with Gmail.
Google Contacts is Google's online contacts management app. Google Contacts allows you to define multiple points of contact (multiple phone numbers, emails, websites).
Google Contacts also allows for easy merge of duplicate contacts and sync with iPhone & Android.
Note that questions here should be primarily concerned with the web interface, and from the perspective of a user, not a programmer.