Once Site Sentry is installed on your website, it checks your website every minute of every day to see if your website is offline or throwing up an error message.
If it is, the Site Sentry support team are immediately alerted and email you to inform you of the situation and what you need to do. All of this is actioned within one minute of your website going down.
Site Sentry is a product of The Web Company. If you already host your website with The Web Company, once the Site Sentry support team are alerted to your website going down, they can immediately access your website and fix the issue as well.