Communication

Communication (also called transmission) is the transfer of information—speech, writing, images, or data—between two or more parties separated by distance. The transfer occurs through electrical signals traveling along wires, radio waves traveling through air, or light traveling through fiber optic cables.

Every communication system has three basic components: a transmitter that converts information into a signal, a channel that carries the signal, and a receiver that converts the signal back into understandable information. Most modern systems allow both parties to transmit and receive simultaneously.

Brief history

Electrical communication began in the nineteenth century when the telegraph was used, converting letters into short and long signals (Morse code). This was followed by the telephone, which transmitted speech directly, and radio, which enabled wireless transmission. In the twentieth century, television, satellite communication, and mobile phones were added. By the end of that century, the Internet had become the infrastructure connecting all these systems.

Analog and digital

Analog systems transmit signals that change continuously and mirror the original sound. Digital systems convert information into numbers (bits) before transmission. Digital transmission can withstand noise better, can be compressed to save bandwidth, and can include codes that detect transmission errors. For this reason, most modern networks have been converted to digital.

Networks and infrastructure

A communication network consists of nodes and links connecting them. Data is divided into small packets, each carrying an address label. Routers at nodes determine the path. This enables multiple transmissions to share the same link simultaneously. The Internet operates according to common protocols such as TCP/IP, which allow different networks to understand each other.

Management and spectrum

Because radio spectrum is a limited resource, it is divided and allocated. Governments have agencies that manage spectrum allocation, license service providers, and set technical standards. At the global level, the International Telecommunication Union (ITU)—a body of the United Nations—coordinates spectrum allocation and shared standards.