It is an application/service that makes use of Internet or mobile Internet to realize synchronous update and backup of address book information.
You can be in any networking equipment such as mobile phone input your contacts on the phone, phone number, relationship between groups, such as information management and update, under your permission, the contacts as you can see his other contact information within the group, so as to realize Shared directory, if the update their contact information, contact your contacts will automatically update, synchronization directory, and leave the old version of the directory information.