We know you’re here to learn about online certificate status protocol (OCSP), but first, imagine if you're a web browser (yes, we're serious). In this scenario, one of your users types in the URL of an SSL-enabled website. Because you're a browser, you're supposed to visit the website, fetch it and show it to your user. So, how would you verify that the certificate of the website is valid?? How do you know whether a certificate authority (CA) hasn’t revoked the certificate?