I am not sure how I add gravity to my game? - python-3.x

Question

I am confused on how I add gravity to my platformer game. I am using pygame for this project. I am relatively new to coding, but anyways here's my code.
import pygame
pygame.init()
win = pygame.display.set_mode((800, 500))
pygame.display.set_caption("Platformer")
x = 200
y = 200
width = 20
height = 20
vel = 5
run = True
FPS = 30
fpsClock = pygame.time.Clock()
while run:
pygame.time.delay(30)
for event in pygame.event.get():
if event.type == pygame.QUIT:
run = False
keys = pygame.key.get_pressed()
if keys[pygame.K_a] and x > 0:
x -= vel
if keys[pygame.K_d] and x < 800 - width:
x += vel
if keys[pygame.K_w] and y > 0:
y -= vel
if keys[pygame.K_s] and y < 500 - height:
y += vel
win.fill((0, 0, 0))
pygame.draw.rect(win, (255, 0, 0), (x, y, width, height))
pygame.display.update()
pygame.display.update()
fpsClock.tick(FPS)
I hope someone can help me get some sort of gravity function working, anything helps. (also what is the best way to make pixelated art, not very relevant to the question)

Answer 1

Gravity just means that the object is moved down a little in each frame:
gravity = 3
while run:
# [...]
y += gravity
if y > win.get_height() - 20:
y = win.get_height() - 20
I suggest to use a pygame.Rect object to represent the player:
import pygame
pygame.init()
win = pygame.display.set_mode((800, 500))
pygame.display.set_caption("Platformer")
player = pygame.Rect(200, 200, 20, 20)
vel = 5
gravity = 3
run = True
FPS = 30
fpsClock = pygame.time.Clock()
while run:
fpsClock.tick(FPS)
for event in pygame.event.get():
if event.type == pygame.QUIT:
run = False
keys = pygame.key.get_pressed()
player.x += (keys[pygame.K_d] - keys[pygame.K_a]) * vel
if player.left < 0:
player.left = 0
if player.right > win.get_width():
player.right = win.get_width()
player.y += gravity
if player.bottom > win.get_height():
player.bottom = win.get_height()
win.fill((0, 0, 0))
pygame.draw.rect(win, (255, 0, 0), player)
pygame.display.update()
pygame.quit()