[PyGame] Why did they put a while loop here?

[Yoriz]

The loop is needed to get user input and to update the display.
The loop will exit if the following statement is true

if event.type == pygame.QUIT:
    running = False

Show the event loop
The most essential part of any interactive application is the event loop. Reacting to events allows the user to interact with the application. Events are the things that can happen in a program, such as a

• mouse click,
  
• mouse movement,
  
• keyboard press,
  
• joystick action.
  

The following is an infinite loop which prints all events to the console:

while True:
    for event in pygame.event.get():
        print(event)

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Quit the event loop properly
In order to quit the application properly, from within the application, by using the window close button (QUIT event), we modify the event loop. First we introduce the boolean variable running and set it to True. Within the event loop we check for the QUIT event. If it occurs, we set running to False:

running = True
while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False

pygame.quit()
Once the event loop, we call the pygame.quit() function to end the application correctly.