Why is my WebApp hosted on a sub domain of Lightcast.com and what is a sub domain even?

A sub domain is a hosting destination of a website (or WebApp, which in essence is a website), pointing to the folders on the server where the files of the website or WebApp are stored. 

In the case of the innovative Lightcast WebApp, the many functionalities of the WebApp - such as on-player functions, registration and user authentication, SSL, DRM and token security - are connected to the proprietary system of Lightcast.com, thus requiring to run under the domain for full and guaranteed functionality. 

It is common to run Web Applications in sub domains on the domain due to security, form functionality and other dependabilities. For example: many free website builders and hosting providers such as Wix.com and Squarespace, run their customer’s websites under a sub domain to their domain, for a variety of technical reasons. 

In the same way the proprietary, and highly technically complex, Lightcast WebApp runs best in sub domains under its servicing domain host.