Simply put, the Internet is a network of many computer networks that exchange data with each other and thus enable the use of various services such as e-mail or the WWW. This is also commonly referred to as surfing. Historically, the Internet has grown out of the Arpanet of the US Department of Defense, which was created at the end of the 1960s. The aim was to use the capacities of several mainframes together in a meaningful way and began to link universities and research institutes.
The Internet nodes are the pivotal points for data exchange and thus an important component of the Internet. These are distributed all over the world and forward data among each other. Usually several, sometimes hundreds, service providers – also called providers – are connected to an Internet node. Within the network node, data is exchanged between the providers. Measured by the amount of data traffic, the world’s largest Internet node is located in Frankfurt am Main, where it is distributed over some 19 data centers.
The providers in turn enable their customers, such as companies or private households, to access the Internet by providing appropriate connections such as DSL or LTE.
Many companies operate their own networks, known as intranets, which become part of the Internet when the connection to the provider is established. While private individuals are usually only users and access information or services, many companies offer Internet services themselves. In addition to the general provision of information, these include online shops, cloud storage or booking portals.
The actual data transmission between the Internet nodes and the providers is carried out worldwide via fiber optic cables, which enable high transmission speeds. The connection of households or companies, also known as the last mile, is usually realized via copper cable, radio and increasingly also via fiber optics. To ensure that everything runs smoothly, the way in which data is exchanged is regulated via so-called protocols.
In the Internet protocol family, for example, it is specified that the data to be transmitted is broken down into small packets at the sender’s end, then transmitted and reassembled at the recipient’s end.
So that a data packet knows where it comes from and where it has to be sent to, each computer involved in the communication is given a unique address, the IP address. This consists of four number blocks separated by dots. Since hardly anyone can remember the IP addresses of the websites visited or other services, there is the Domain Name System (DNS). With this system, instead of IP addresses, the Internet can be used to create meaningful names for websites, or more precisely, Internet servers. These are known as Internet addresses, www addresses or URL.