Use your mirrors when stopped at an intersection:
To see if vehicles parked on the sides of the street are entering traffic.
To look for vehicles changing lanes.
To watch for vehicles behind you that may not be slowing down.
To see if someone is planning to turn behind you.
When you are stopped at an intersection, use your mirrors to check for cars approaching you from behind. The drivers may not notice you until they are too close and you may need to react.