The short answer
IPTV stands for Internet Protocol Television. It delivers television and video using an internet connection rather than only relying on terrestrial, satellite, or cable broadcast infrastructure.
From provider to screen
A provider prepares streams and makes them available through an access method. A compatible player on your device receives that information and organizes it for viewing.
What you need
You generally need stable broadband, a compatible device, a reputable player, and valid access details from your provider. Features and available content vary by service.
A responsible reminder
Choose reputable applications, protect your access details, and use services in line with their terms and the laws that apply where you live.