Internet

Terminology and History - The word 'internetted' was used as early as 1849, meaning interconnected or interwoven. - The word 'Internet' was used in 1945 by the United States War Department in a radio operator's manual and in 1974 as the shorthand form of Internetwork. - Today, the term 'Internet' most commonly refers to the global system of interconnected computer networks, though it may also refer to any group of smaller networks. - Most publications treated the word 'Internet' as a capitalized proper noun when it came into common use, but this has become less common. - The lowercase form of 'internet' is now recommended in every case, although it may still be capitalized to distinguish the global internet from smaller networks. - In the 1960s, computer scientists began developing systems for time-sharing of computer resources. - J. C. R. Licklider proposed the idea of a universal network while working at Bolt Beranek & Newman and later leading the Information Processing Techniques Office (IPTO) at ARPA. - Research into packet switching, one of the fundamental Internet technologies, started in the early 1960s. - The ARPANET, an experimental resource sharing network, was designed incorporating packet switching from the proposed NPL network. - The ARPANET development began with two network nodes interconnected between UCLA and SRI International on October 29, 1969. - The ARPANET gradually developed into a decentralized communications network, connecting remote centers and military bases in the United States. - Other user networks and research networks, such as the Merit Network and CYCLADES, were developed in the late 1960s and early 1970s. - International collaborations for the ARPANET were rare initially, but connections were made in 1973 to the Norwegian Seismic Array (NORSAR) and Peter Kirstein's research group at University College London. - ARPA projects, international working groups, and commercial initiatives led to the development of protocols and standards for multiple separate networks to become a single network or a network of networks. - In 1974, Vint Cerf and Bob Kahn published a proposal for A Protocol for Packet Network Intercommunication, using the term 'internet' as a shorthand for 'internetwork.' Impact - The Internet reshaped and redefined traditional communication media such as telephone, radio, television, paper mail, and newspapers. - New services such as email, Internet telephone, Internet television, online music, digital newspapers, and video streaming websites emerged. - Print publishing adapted to website technology or transformed into blogging, web feeds, and online news aggregators. - The Internet enabled new forms of personal interaction through instant messaging, Internet forums, and social networking services. - Online shopping grew exponentially, allowing businesses to extend their presence and affect supply chains across industries. Governance - The Internet has no single centralized governance in technological implementation or policies for access and usage. - Each constituent network sets its own policies. - The Internet Corporation for Assigned Names and Numbers (ICANN) directs the Internet Protocol address (IP address) space and the Domain Name System (DNS). - The Internet Engineering Task Force (IETF) is responsible for the technical underpinning and standardization of the core protocols. - The IETF is a non-profit organization of international participants that anyone may associate with by contributing technical expertise. Infrastructure - Internet consists of hardware components and software layers. - Components include routers, media, repeaters, modems, etc. - Network nodes are not necessarily Internet equipment. - Internet packets are guided by IP routers. - Internet runs across heterogeneous hardware. - Packet routing involves multiple tiers of ISPs. - Tier 1 networks exchange traffic directly via high-speed fiber-optic cables. - Tier 2 and lower-level networks buy Internet transit. - ISPs may use upstream providers or implement multihoming. - Large organizations may perform the same function as ISPs. - Common methods of Internet access include dial-up, broadband, Wi-Fi, satellite, and cellular technology. - Internet access points exist in public places like libraries and coffee shops. - Wi-Fi provides wireless access to the Internet. - Wireless community networks have been established. - Commercial Wi-Fi services cover large areas in many cities. Internet Protocol and Subnetwork - Internet protocol suite is a framework for communication. - Consists of four conceptual layers: application, transport, networking technologies, and Internet layer. - Application layer includes protocols like HTTP and data structures like HTML. - Transport layer provides ordered, reliable delivery (TCP) or unreliable datagram service (UDP). - Networking technologies interconnect networks and exchange traffic. - Implements the Internet Protocol (IP) for computers to identify and locate each other. - IP layer code is independent of the network type it runs over. - Link layer connects nodes on the same physical link. - Link layer protocols do not require routers for traversal to other links. - Encapsulation information is added at each abstraction layer during data transmission. - IP addresses are used to direct internet packets to their destinations. - IP addresses consist of fixed-length numbers within the packet. - IP addresses can be assigned automatically via DHCP or configured manually. - Domain Name System (DNS) converts domain names to IP addresses for routing purposes. - IPv4 and IPv6 are the two versions of the Internet Protocol. - IPv4 defines an IP address as a 32-bit number. - IPv4 is still in dominant use on the Internet. - IPv4 was designed to address up to approximately 4.3 billion hosts. - IPv4 address exhaustion began in 2011. - The global IPv4 address allocation pool is now exhausted. - IPv6 provides larger addressing capabilities and more efficient routing. - IPv6 uses 128 bits for the IP address. - IPv6 was standardized in 1998. - IPv6 deployment has been ongoing since the mid-2000s. - IPv6 is not directly interoperable with IPv4. - Subnetwork is a logical subdivision of an IP network. - Computers in a subnet have identical most