WebTV is an alternative to accessing the internet through a personal computer. Through the proprietary WebTV browser users can access email and website and the "value-added" interactive dimension promised by digital television.*
As for the quality of interaction; the user must use a modified remote control to select options and a wireless keyboard for typing, television screens have not been designed with on screen reading in mind and HTML support is equivalent to Internet Explorer 3.
*A clickable pizza commercial that allows are user to order through their TV is often touted as a successful example.