What is when an identity thief calls or emails you pretending to be someone else in order to get your personal information

The answer is: Pishing

Pishing perpetrators usually steal the information by pretending to be either family members or some sort of authoritative figure to ask for your information.

Rather than knowledge in computer, the perpetrators of pishing tend to be really good at social engineering since they obtain what they want by making the victims give up the information voluntarily.