Electronics is a field of engineering and applied physics that grew out of the study and application of electricity. Electricity concerns the generation and transmission of power and uses metal conductors. Electronics manipulates the flow of electrons in a variety of ways and accomplishes this by using gases, materials such as silicon and germanium that are semiconductors, and other devices like solar cells, light-emitting diodes (LEDs), masers, lasers, and microwave tubes. Electronics applications include radio, radar, television, communications systems and satellites, navigation aids and systems, control systems, space exploration vehicles, microdevices like watches, many appliances, and computers.
Telecomunication is the transmission of signals over a distance for the purpose of communication. In modern times, this process typically involves the sending of electromagnetic waves by electronic transmitters, but in earlier times telecommunication may have involved the use of smoke signals, drums or semaphore or heliograph. Today, telecommunication is widespread and devices that assist the process, such as the television, radio and telephone, are common in many parts of the world. There are also many networks that connect these devices, including computer networks, public telephone networks, radio networks and television networks. Computer communication across the Internet is one of many examples of telecommunication.
Telecommunication systems are generally designed by telecommunication engineers. Early inventors in the field include Alexander Graham Bell, Guglielmo Marconi and John Logie Baird. Telecommunication is an important part of the world economy with the telecommunication industry revenue being placed at just under 3 percent of the gross world product.