The Emergency Room (More commonly referred to as "The Pit" or the "ER") is where patients are taken in following an emergency requiring medical treatment, including transfers from other neighboring hospitals. The medical treatment required can be severe or minor, ranging from major surgery to a simple prescription.
The Grey Sloan Memorial Hospital ER is equipped with (at least) three trauma rooms, multiple cubicles and crash carts containing ALS (Advanced Life Support) drugs and equipment. There is an ambulance bay outside an entrance to the ER where staff will meet incoming ambulances.
The surgical staff at Grey Sloan Memorial Hospital who are on-call for the ER will usually remain in the ER, performing scut work (usually sutures) and conducting surgical consults when requested for and by ER physicians who will then sign off the patient to the surgical team if necessary.
Traditionally, an emergency medicine head/attending runs the ER, however, Dr. Owen Hunt, as the hospital's trauma head, is the de facto leadership of the ER.