Data or voice communications via digital or analog lines, and increasingly, wireless systems such as Ricochet Modems, cellular phones, pagers, and satellite systems such as Iridium and DirecPC. Without telecommunications, you wouldn't be reading this. Telecommunications began with the invention of the telephone by Alexander Graham Bell in the early 20th century.

Communications over a distance. Covers everything, data, voice, video, smoke signals. Telecom is a shortened but perfectly acceptable alternative. First electronic telecommunications device in widespread use was the telegraph. Telephony is a related term that originally just meant voice over phone lines and has been mostly replaced by telecom.