Pauses until a certain condition has been satisfied.
For example, wait for an image to be loaded.
Selenium WebDriver uses a combination of the classes WebDriverWait and ExpectedConditions to add explicit waits.
example
from selenium import webdriver
from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC
driver = webdriver.Firefox()
driver.get('http://www.python.org')
try:
element = WebDriverWait(driver, 10).until(EC.presence_of_element_located((By.ID, "start-shell")))
finally:
driver.quit()