Error Message: 'chromedriver' executable needs to be PATH

I just started on Selenium and was able to load up google but now when I run the following code it produces the error:

selenium.common.exceptions.WebDriverException: Message 'chromedriver' executable needs
to be PATH. Please see https://sites.google.com/a/chromium.org/chromedriver/home

Why is it saying "C:Users/Colin/Python/chromedriver" is not a path?

from selenium import webdriver

browser = webdriver.Chrome("C:Users/Colin/Python/chromedriver")
browser.get('http://www.google.com')

browser.quit()