Every custom object, except Detail objects in a Master-Detail relationship, has a corresponding sharing object to store its record-level sharing rules. The sharing object is created automatically by Force.com and is invisible to the native user interface. It can be seen in the Force.com IDE’s Schema Explorer. Its name is the name of your object with
__Share appended. For example, the sharing object for the
Project__c object is
The sharing object contains explicit sharing rules. These are created by Force.com managed sharing, user managed sharing, and Apex managed sharing. It does not contain implicit shares such as organization-wide defaults.
Four fields of the sharing object control how records are shared between ...