An Anti-pry plate (also known as a Latch Shield or Latch Guard) is a strip of metal used to cover the space between the edge of the door and the door frame, thus preventing someone from being able to use an object to pry the door open. Some only cover where the door latch is and others cover the entire length of the door. Pry-plates can be purchased at various places online and some retail hardware stores such as Home Depot or Lowe's.
