MC

Internet and the World Wide Web

What is the Internet?

  • The Internet is a global system of interconnected computer networks using the TCP/IP protocol suite.
  • It supports a wide range of information resources and services, including the WWW and email.
  • Traditional media like telephone, music, film, and television have been reshaped by the Internet.

History of the Internet

  • The Internet's origins are traced back to the 1960s with the U.S. government's ARPANET, designed to be robust and fault-tolerant.
  • ARPANET was used for data sharing between universities and government facilities.
  • The National Science Foundation (NSF) and NASA further developed networks in the 1980s.
  • NSFNET was decommissioned in 1995 and replaced by commercial Internet Service Providers, leading to popularization and widespread use.

Modern Infrastructure

  • High-speed fiber optic lines (OC lines) connect regions, cities, and continents.
  • Examples of OC line speeds:
    • OC-1: 51.84 Mbit/s
    • OC-3: 155.52 Mbit/s
    • OC-12: 622.08 Mbit/s
    • OC-24: 1,233.16 Mbit/s
    • OC-48: 2,405.37 Mbit/s
    • OC-192: 9,621.50 Mbit/s
    • OC-768: 39,813.12 Mbit/s (39.8 Gbit/s)
  • Undersea fiber optic cables connect continents, with some spanning over 12,000 miles.

Governance

  • No single entity owns the Internet; it is made up of networks owned by various organizations.
  • ICANN directs the Internet Protocol address space and Domain Name System.
  • The IETF standardizes core protocols like IPv4 and IPv6.
  • The Internet Governance Forum (IGF) discusses Internet-related issues.

How the Internet Works

  • The Internet facilitates communication through web browsing, email, and video.
  • Two basic models for communication:
    • Circuit switching: Establishes a reliable, semi-permanent connection.
    • Packet switching: Data is broken into packets and sent independently (TCP/IP).

Client-Server vs. Peer-to-Peer

  • Client-server: Servers provide resources, and clients request them.
  • Peer-to-peer (P2P): Peers share resources directly without central coordination.

Protocols

  • Protocols are rules for communication between computers.
  • Common protocols:
    • HTTP: WWW communication
    • SMTP: Email
    • FTP: File transfer
    • POP3: Web-based email clients
    • VoIP: Internet telephony

Networks

  • LAN (Local Area Network): Connects computers in a local area.
  • Internet: A global network of interconnected networks.
  • Intranet: A network for local communication only.
  • Extranet: Allows controlled access to select information on a network via the Internet.
  • Communications can be secured using VPN technology and HTTPS.

Cloud Computing

  • Cloud computing: Accessing server-based computational resources via a network.
  • Applications and data are managed remotely by the cloud server.

Addressing

  • URLs (Uniform Resource Locators) specify the location of resources and the retrieval mechanism.
  • IP addresses are numeric addresses that uniquely identify machines.
  • The Domain Name System (DNS) automatically looks up numeric addresses for URLs.

World Wide Web

  • The WWW is a system of interlinked hypertext documents accessed via the Internet.
  • It is one of the services that run on the Internet and consists of interconnected documents and resources linked by hyperlinks and URLs.
  • Web pages are viewed using a web browser.