The ME Card (also known as your Sync.ME Profile) is similar to a contact card. This is a unique profile with your contact details where you choose how you want other Sync.ME users (users who already have your phone number) to view you. These "cards" differ from regular contacts by the fact that they are always up-to-date.
If someone has your phone number he or she can sync with your ME Card and view your photo and information. Anytime you edit the details on your ME Card, this will change on your friends' Sync.ME app as well. So, if you change your phone number in your ME Card then your friends in Sync.ME will be able to see the changed number. This way, you will not have to send out emails or texts to your friends when you change your number (or any other contact info).
A few Notes:
1. Users must already have your phone number in their contact list in order to sync with your ME Card. Sync.ME does not automatically give out phone numbers to other users.
2. ME Card photos take priority over the other social networks. For instance, if you have a contact with a ME Card and he is also synced with Facebook or LinkedIn, the ME Card photo will be the main photo for this contact.