What is a vital element in Earth's atmosphere that helps it support life when other planets can't? A) The element of surprise
B) Hydrogen
C) Oxygen
D) Carbon dioxide

Are you asking about a street map usage  if so here is your answer  a street map for a very limited area could simply be a bit map or a .jpg image.  but a more general map would probably store the streets as vectors.  but you shouldn't assume that there is one way to do it