When you enable analytics for a website it will automatically track all page views within the configured URLs. But if you want to know more about what your users do on your web you need to send additional data to Extellio as a custom event. An event is basically built with four bricks, out of which only two are required:   Category (Required) - This describes the type of event you want to track, e.g Clicks, Element visibility or Videos.  Action (Required) - This defines the