When we request an object from the Graph API, without explicitly specifying the data fields we're interested in, we receive a default set of properties for that object, properties which are determined by Facebook.
Alternatively, we can improve the efficiency of our requests by explicitly listing the data fields we're interested in, and the API will only return those properties.
For example, were we seeking information about user's birthdays, rather than loading all of the user's information—including their name, gender, and locale—with each request, we could specify that we only want to load that user's birthday information, via the birthday
data field.
Specifying data fields in this manner obviously doesn't give us access to information that a user hasn't supplied, and it doesn't bypass any privacy restrictions that the user has set up for their data, but it does ensure that responses from the Graph API will return that information if it...