Computer network

Computers can talk to each other.

This is called a network. Computers use wires to share things. They can use thin glass threads too.

These glass threads use light to send data. Some computers talk without any wires at all. They use radio waves through the air.

This helps computers connect all over the world. It lets us send mail and watch videos. Networks are everywhere today!

A computer network is a group of connected computers.

These computers talk to each other to share data. They are called hosts. To find each host, the network uses an address. This is like a home address for a computer. Some hosts also have hostnames. These are easy names that people can remember.

Computers can connect in many ways. Some use copper cables. Others use optical fibers. These are thin glass threads. They use light to send data very fast. Some networks use no wires at all. They use radio waves to talk through the air.

This helps connect computers across the whole world. The way hosts are arranged is called a network topology. The first network started in 1940. George Stibitz connected a computer at Dartmouth to one at Bell Labs. Today, almost all computers use networks. We use them to send email or watch videos. We also use them to visit the World Wide Web.

A computer network is a group of connected computers and other devices.

These devices are often called hosts. They use special rules called communication protocols to share data. Every host has a network address so the hardware can find it. You can also use hostnames, which are easy names for people to remember.

The way these hosts and hardware are arranged is called a network topology. Networks are very important today. They let us use the World Wide Web and send emails. They also help us watch digital videos and use printers.

Networks work by sending information through different types of paths.

Some networks use wired media like copper cables. Other networks use optical fibers, which are thin glass threads. These fibers carry pulses of light to move data very quickly. Some networks do not use wires at all. They use wireless radio-frequency media to send signals through the air.

This allows devices to talk to each other without being plugged in. Different technologies, like Ethernet, help manage how this data flows.

People have been building networks for a long time.

The very first network happened in 1940. A man named George Stibitz connected a terminal at Dartmouth to a computer at Bell Labs. This showed that computers could work together over long distances. In the late 1950s, the U.S. military built a network for a radar system. This used the Bell 101 modem, which was the first commercial modem. It could send data at a speed of 110 bits per second.

Many scientists helped make the modern internet possible.

In the 1960s, Paul Baran and Donald Davies both invented packet switching. This is a way to send message blocks across a network. Later, the ARPANET began in 1969. It connected four nodes, including the University of California at Los Angeles. In 1973, Robert Metcalfe and David Boggs created Ethernet at Xerox PARC. Vint Cerf and Bob Kahn also wrote a famous paper about internetworking in 1974. Their work helped create the Transmission Control Protocol, or TCP.

Today, networks are part of almost everything we do.

Most computers are connected to the global Internet. We even find small networks inside cars and airplanes. This is called embedded networking. You might use a network to access a storage server or an instant messaging app. Even the cables under the ocean connect different continents together. These huge systems allow the whole world to stay connected through data.

A computer network is a group of communicating computers and peripherals. These devices are known as hosts. Hosts share data with one another using specific rules called communication protocols. Networking hardware facilitates this exchange of information. To make this work, every host is identified by a network address. This address allows the hardware to locate and identify specific devices. Hosts can also use hostnames. These are memorable labels for host nodes. A name server, such as the Domain Name Service, can map these hostnames to network addresses.

Networks rely on a physical medium to exchange information. This medium can be wired or wireless. Wired media include copper cables and optical fibers. Optical fibers are thin glass threads that carry pulses of light. These light pulses represent data and are sent via lasers and optical amplifiers.

Using a method called dense wave division multiplexing, optical fibers can carry multiple data streams at once. This allows for speeds up to trillions of bits per second. Other wired options include coaxial cable and twisted pair cabling. Twisted pair cables use four pairs of copper wires. The wires are twisted to reduce electromagnetic induction and crosstalk. Wireless networks use radio-frequency media to send signals through the air.

The arrangement of hosts and hardware is called a network topology. This structure determines how data flows through the system. Different technologies manage these flows. Ethernet is a very common family of technologies used in local area networks, or LANs. Ethernet uses copper or fiber media to connect devices. In 1973, Robert Metcalfe and David Boggs created Ethernet at Xerox PARC. It was inspired by the ALOHAnet radio system. Ethernet has scaled significantly over time. In 1980, it moved to a 10 Mbit/s protocol. By 1995, speeds reached 100 Mbit/s. By 1998, it supported 1 Gbit/s. Today, Ethernet can reach speeds of 800 Gbit/s.

The history of networking began with early experiments in remote computing. In 1940, George Stibitz connected a terminal at Dartmouth to a computer at Bell Labs. This was the first real-time, remote use of a computing machine. In the late 1950s, the U.S. military built the SAGE radar system network. This used the Bell 101 modem, which was released by AT&T in 1958. This modem was the first commercial modem for computers. It could transmit digital data at 110 bits per second over telephone lines. In 1959, Christopher Strachey filed a patent for time-sharing in the United Kingdom. During the same year, John McCarthy started a project at MIT to implement time-sharing.

Significant breakthroughs occurred in the 1960s regarding how data is moved. Paul Baran and Donald Davies independently invented packet switching. Packet switching is the concept of sending data in small blocks. Baran focused on adaptive routing across distributed networks. Davies developed a hierarchical design that included high-speed routers and protocols. These inventions were seminal for modern communication. In 1969, the ARPANET was established. It was based on J. C. R. Licklider's idea of an "Intergalactic Computer Network." The first four nodes were connected between UCLA, the Stanford Research Institute, UC Santa Barbara, and the University of Utah.

Mathematical modeling and international connections helped expand these systems. Leonard Kleinrock performed mathematical work to model packet-switched networks. His work on message delay and hierarchical routing remains critical to the Internet today. In 1973, Peter Kirstein connected the ARPANET to British academic networks. This was the first international heterogeneous computer network. Later, in 1974, Vint Cerf and Bob Kahn published a paper on internetworking. They also wrote the first Transmission Control Protocol, or TCP, specification. This work led to the term "Internet" being used as shorthand for internetworking.

Today, networks are essential for almost all modern technology. They support the World Wide Web, email, and instant messaging. They also power digital video, audio, and storage servers. Most computers are connected to the global Internet. We also see embedded networks in many electronic devices. These are found in cars, airplanes, and factories. Even the physical connections are massive. Long-distance optical fiber cables run under the ocean to connect continents.

These vast systems allow data to move across the entire planet constantly.