A hit occurs when a browser tries to request a file from your account. When a visitor tries to load a page, their browser will first try to request the main page contents from your account. After that, it will also request any included content, like styling files, scripts and images. Each of those requests is a “hit”, and they are all counted towards the daily hits limit.
If your account receives more than 50,000 of these hits on a single day, your website may be taken down.