driver.close() and driver.quit() are two different methods for closing the browser session in Selenium WebDriver.

driver.close() - It closes the the browser window on which the focus is set.

driver.quit() – It basically calls driver.dispose method which in turn closes all the browser windows and ends the WebDriver session gracefully.

You should use driver.quit whenever you want to end the program. It will close all opened browser window and terminates the WebDriver session. If you do not use driver.quit at the end of program, WebDriver session will not close properly and files would not be cleared off memory. This may result in memory leak errors.

You're actually creating a second Selenium session in your tearDown() function. You need to put the session created in setUp() into an instance variable, then close that session in tearDown().

class TestFoo(unittest.TestCase):
    def setUp(self):
        self.selenium = selenium('localhost', 4444, "*chrome", 'http://blackpearl/')
        self.selenium.start()

    def tearDown(self):
        self.selenium.stop()

    def test_bar(self):
        self.selenium.open("/somepage")
        #and so forth

I have worked with Web Driver in both java and C# and I use

In Java :

WebDriver driver;      
driver.quit();

In C# :

IWebDriver Driver;
Driver.Quit();

In Python, using selenium webdriver for Chrome, I needed to call stop_client() before close():

from selenium import webdriver

in setUp():

options = webdriver.chrome.options.Options()
options.add_argument("--disable-extensions") # optional and off-topic, but it conveniently prevents the popup 'Disable developer mode extensions' 
self.driver = webdriver.Chrome(chrome_options=options)

In tearDown():

self.driver.stop_client()
self.driver.close()

WebDriver driver;      
driver.quit();

Above will close all open browser windwos.

And

WebDriver driver;      
driver.close();

This will close current browser window in focus.

Using TestNG and Java.
Assume this method is located in some BaseTest class which is inherited by test class, so try this:

@AfterClass(alwaysRun = true)
protected void tearDown() {
    driver.quit();
    driver = null;
}

You can use either driver.close(); or driver.quit();.

Use close() for one browser to close and quit() is to close all browsers using webdriver. But why close() is not closed at runtime, but it is closed at debugging I don't know.

This is what worked for me:

    taskkill /f /fi "pid gt 0" /im iexplore.exe

I have this in my pre-build events in the Visual Studio Solution. This is can be run from the command line, just call it in your project and you should be all set.

I also have the following line to close the the IE driver in case of failure to execute driver.Quit() or .Close()

  taskkill /f /fi "pid gt 0" /im IEDriverServer.exe

If you use headless mode you still see them not closing try this solution 1) Get the driver as singleton

@Singleton
class BrowserInstance {

ChromeDriver getDriver(){
    ChromeOptions options = new ChromeOptions()
    options.addArguments("--headless --disable-gpu")
    return new ChromeDriver(options)
   }
}

2) Use Close and quit in finally block

 finally {
        chromeDriver.close()
        chromeDriver.quit()
    }

Result: you will be using only one instance at time and if you see task manager you will not find chromedriver and chrome process hanging.

Maybe my solution will be not a super smart one, but before each automated test case I put:

time.sleep(2) driver = webdriver.Chrome()

driver.implicitly_wait(10)

Maximizes the window

driver.maximize_window()

And to close all windows of the test case I use:

def close(): driver.close() close()

And this works for me in Python.