Shopping List Redux Error?

Traceback (most recent call last):                                                                                                                             
  File "function_list.py", line 25, in <module>                                                                                                                
    add_to_list(new_item)                                                                                                                                      
  File "function_list.py", line 8, in add_to_list                                                                                                              
    shopping_list.append(item)                                                                                                                                 
AttributeError: 'dict' object has no attribute 'append' 

shopping_list = {}

def show_help():
  print("What should we pick up at the store?")
  print("Enter DONE to stop.")

def add_to_list(item):
  shopping_list.append(item)
  print("Added! List has {} items.".format(len(shopping_list)))

def show_list():
  print("Here's your list:")
  for item in shopping_list:
    print(item)

show_help()

while True:
  new_item = input("> ")
  if new_item == "DONE":
    break
  elif new_item == "HELP":
    show_help()
    continue
  add_to_list(new_item)
  continue

show_list()