Telecommunications, also known as telecom, is the exchange of information over large distances. It's a broad term that includes various sectors, but all include a transmitter and a receiver. The medium of signal transference can be via various means—fiber, electromagnetic fields, light, cable, etc.
The internet is a large example of telecoms, dwindling to smaller wide-area networks (WANs), telephone, WhatsApp messaging, emails, and broadcast networks, including radio and television. Voice was the original medium of communications, but these days, video, data, and text are also sent back and forth to communicate.
People generally refer to telecommunications as a product and a system and service provided by larger corporations. Telecommunications service providers provide the service that allows individuals and businesses to do everyday tasks to communicate with others.