The square in pygame will not move to keypress

Question

Do I have to use pygame.display.flip() or pygame.display.update()?

running = True
while running:
  for event in pygame.event.get():
    if event.type == pygame.QUIT:
      running = False
      if event.type == pygame.KEYDOWN:
        if event.key == pygame.K_d:
          x += 1
          surface.fill((0,0,0))
          pygame.draw.rect(surface, color, pygame.Rect(x, y, 60, 60))
          pygame.display.update()

Answer 1

The Keydown check is never reached, please use:

running = True
while running:
  for event in pygame.event.get():
    if event.type == pygame.QUIT:
      running = False
    if event.type == pygame.KEYDOWN or event.key == pygame.K_d:
      x += 1
      surface.fill((0,0,0))
      pygame.draw.rect(surface, color, pygame.Rect(x, y, 60, 60))
      pygame.display.update()