Sling is a subscription service, like Netflix, but instead of a library of movies and shows, you subscribe to Live TV streams of channels normally only available from a cable TV subscription. It's all fully legal and above board, as they pay the same licensing fees that a Comcast would.
As the other poster mentioned, like Netflix, you need an internet connection. If you want to watch it on your TV screen, a set-top box like a Roku or AppleTV is worthwhile but you could always plug your laptop into the TV instead.
As the other poster mentioned, like Netflix, you need an internet connection. If you want to watch it on your TV screen, a set-top box like a Roku or AppleTV is worthwhile but you could always plug your laptop into the TV instead.