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Visualization of the Internet from Opte project data (15 January 2005)
The Internet (from the English interconnected networks - connected networks; colloquially: net, network) is a publicly available worldwide system of interconnected computer networks that transmit data using packet data switching using the standardized Internet Protocol (IP) and many other protocols. It consists of thousands of smaller commercial, non-commercial, academic, private, government and military computer networks. It serves as a transmission medium for various information and services such as e-mail, chat and especially the system of interconnected hypertext documents (web pages) and web applications called the World Wide Web (WWW). The Internet does not have a single, centralized management of technology implementation or access and use policies. Each network that is part of it sets its own policies. The common definitions of the two main pillars of the Internet: the Internet Protocol Address Space (IP address) and the Domain Name System (DNS) are managed by the Internet Corporation for Assigned Names and Numbers (ICANN). Technical support and standardization of basic protocols is the activity of the Internet Engineering Task Force (IETF).


Today's Internet
In addition to the complex physical connections that make up the structure of the Internet, the Internet also exists thanks to multilateral agreements (e.g. "peering agreements" and technical specifications or protocols that determine how data is to be exchanged over the network).

Unlike legacy communication systems, the Internet Protocol Suite was deliberately designed to be agnostic with respect to the physical medium on which it runs. Any communications network, fixed or wireless, that is capable of transmitting two-way digital data can carry Internet traffic. Therefore, Internet packets can be transmitted over fixed networks such as copper wire, coaxial cable and optical cable, as well as wireless networks such as Wi-Fi. All these networks sharing the same set of higher-level protocols make up the Internet.

Internet protocols originate from discussions within the Internet Engineering Task Force (IETF) and its working groups, which are open to public input and revision. These committees produce documents known as Request for comments (RFC). Some RFCs are promoted by the Internet Architecture Board (IAB) to Internet standards.

The most commonly used Internet protocols in the Internet Protocol Suite include IP, TCP, UDP, DNS, PPP, SLIP, ICMP, POP3, IMAP, SMTP, HTTP, HTTPS, SSH, Telnet, FTP, LDAP, SSL, and TLS.

Services that use these protocols are e-mail, Usenet newsgroups, World Wide Web, Gopher, session access, WAIS, finger, IRC, MUDy and MUSHe. The most used of these are e-mail and the World Wide Web, with many other services based on them, such as mailing lists, blogs and podcasts. The Internet enables the provision of real-time services such as telephone calls, Internet radio and Internet (television) broadcasting, which are thus accessible anywhere in the world.

Some other popular Internet services did not originate in this way, but were originally based on proprietary systems. These include IRC, ICQ, AIM and Gnutella.

There have been many analyzes of the Internet and its structure. For example, the IP routing structure of the Internet and the hypertext links of the World Wide Web have been found to be examples of scale-free networks.

Similar to how internet providers connect via internet exchange points (e.g. SIX – Slovak Internet eXchange), research networks tend to connect to large subnets such as:

These, in turn, are built around relatively small networks.

Current and potential problems
In addition to the advantages, the Internet has also brought some problems and negatives. Some of them received a lot of publicity.

They mainly include:

child abuse related to child pornography
copyright infringement
spread of computer viruses
computer security attacks
outdated technology
In democratic societies, the Internet has gained new significance as a political tool. Howard Dean's 2004 presidential campaign in the United States became known for its ability to secure sponsorships over the Internet.

Some governments, such as those in Cuba, Iran, the DPRK, Myanmar, China, or Saudi Arabia, restrict what people in their countries can access on the Internet. These are mainly restrictions on access to political and religious content. They achieve this by filtering domains and content so that it is not easily accessible without elaborate procedures.

In Norway, Denmark, Finland[1] and Sweden, the major Internet providers have agreed to restrict sites designated by the police. Despite the fact that the list of banned URLs should contain only the addresses of known sites with child pornography, the content of the list is kept secret.

A number of countries, incl

of the United States, although it has legally designated the possession or distribution of certain materials, such as child pornography, as illegal, they do not use filtering software. There is a lot of free and commercial software with which the user can choose to block objectionable sites, individual computers or entire networks, for example to limit children's access to pornography or violent content. Internet access The usual method of access is a dial-up connection (so-called dial-up via a classic fixed telephone line), which is the slowest. The other one is via ISDN telephone line, it is about twice as fast but nowadays it is being replaced by DSL telephone lines. Other methods are broadband access via coaxial cable using cable television distribution, or optical cable (so-called FTTH) and access via satellite. There is also access to the Internet through the 220V electrical grid network, which is suitable for apartment buildings. Modems with this technology work up to a distance of 200 m (transmission speed up to 200 Mbps) and there are so-called bridging links to connect two phases, that means you can also connect a neighbor who lives in the next door in the block. So far, however, the technology is only suitable for wiring inside an apartment building. The European Union finances a research and development project to support this method of connecting to the PowerNet Internet. Public places where it is possible to use the Internet are Internet cafes and libraries around the world. Access points can also be found in public places - airport waiting rooms, in some trains, in the squares of larger cities. Wi-Fi provides wireless access to computer networks and can therefore also be used to access the Internet itself. Hotspots that allow such access are found in public places and it is necessary to have your own device with a Wi-Fi card. These services can be free for everyone, only for customers or for a fee. Hotspot is not limited by an enclosed space. There are entire campuses and parks, even entire neighborhoods with access. In the US, broadband access using power lines was approved in 2004 despite strong protests from the amateur radio community. The problem with modulating an overhead high-voltage line is that the entire line acts like a giant antenna, completely blocking the long-wave radio frequencies used by amateurs, sailors, and others. Countries where the Internet is a commodity used by the majority of citizens are Iceland, Sweden, Australia, Denmark, the United States, Canada, the United Kingdom, the Netherlands, Japan, the Republic of Korea and Norway. In the last decade of the 20th century, the number of Internet users grew rapidly, although this development slowed down somewhat after 2000. The phase of rapid growth in industrialized countries ends with these technologies being deployed routinely, but growth continues in Africa, Latin America, the Caribbean, the Middle East and Slovakia. Internet access is unevenly distributed between low and high speed connections. ADSL and other broadband technologies are rare or non-existent in most developing countries, and even in developed countries their penetration may be limited by high costs and average performance (most Eastern European countries and the United States), while low prices and high performance attract large numbers of customers ( Scandinavia, France). Even within a country, there can be differences between larger cities (which often have multiple broadband providers) and other areas (where there is often no broadband access). Spreading the availability of the Internet is a way to bridge the so-called digital barrier (digital divide).


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