Internet Protocol Television sends a continuous stream of video packets over regular broadband instead of through satellite dishes or coax. The provider hosts encoders, middleware and origin servers that repackage each channel into adaptive HLS or DASH streams, so the subscriber only needs an app and a stable connection.
There are three primary formats: live linear channels, time-shifted television (catch-up and start-over) and video-on-demand libraries. All of them are addressed by URLs and can share the same middleware for authentication, analytics and billing.
Legal IPTV services always have contracts with rights owners. Ask the provider for a partner list, verify that its domains are whitelisted on your devices, and make sure payments go through reputable acquirers. That is the easiest way to distinguish legal IPTV from shady restreams.