A global computer network providing a variety of information and communication facilities, consisting of interconnected networks using standardized communication protocols. It is a massive public spider web of computer connections. It connects personal computers, cell phones, GPS units etc.

Advanced Research Project Agency Network (ARPANET) system is the technical foundation of the Internet was discovering in 1969. In 1989, Internet is popular as world’s largest network for because WWW.

Type of Networks: There are several different types of computer networks.

  1. LAN: Local Area Network connection by Cable and speed 10-100 Mbps.
  2. MAN: Metropolitan Area Network connection by Electromagnetic Wave and speed 10-100 Mbps.
  3. WAN: Wide Area Network connection by Satellite.
  4. WLAN: Wireless Local Area Network connection by WiFi and speed 1 to 54 Mbps after manufacture 108 Mbps. Access point within a radius of 65 to 300 feet.
  5. SAN: Storage Area Network

Advantages of Internet:

  1. E-mail (ই-মেইল)
  2. Information (তথ্য)
  3. Online Services (অনলাইন সেবাসমূহ)
  4. E-commerce (ই-কমার্স)
  5. Software Downloads (সফটওয়্যার ডাউনলোড)
  6. Communication (যোগাযোগ)
  7. Entertainment (বিনোদন)

Disadvantages of Internet:

  1. Theft of Personal information (ব্যক্তিগত তথ্য চুরি)
  2. Internet addiction (ইন্টারনেট আসক্তি)
  3. Virus attack (ভাইরাস আক্রমণ)
  4. Spamming (বোকা)

Essential elements to connect with internet:

  1. Personal Computer
  2. Telephone Line
  3. ISP Connection (ISP- Internet Service Provider)
  4. Modem
  5. IP Address (Ex.
  6. Browser (Ex. Internet Explorer, Google Chrome, Mozilla Firefox)

IP Address: The computer is identified by an “address”. An IP (Internet protocol) address is an identifier for a particular machine on a particular network. An IP address consists of four sections, separated by periods and each section contains a number ranging from o to 255. (Example:

Transmission Control Protocol/Internet Protocol (TCP/IP): TCP/IP is actually a collection of protocols or rules. It governs the way through which data travels from one machine to another across networks.

Topology: The physical configuration of a network that determines how the network’s computers are connected.

1. Ring Topology:
2. Mesh Topology
3. Star Topology
4. Bus Topology
5. Hybrid Topology

Web Browser: A browser is software which acts as an interface between the user and inner working of the internet, specifically the World Wide Web. A browser based on graphics or text for make the internet easier to use. Example: Internet Explorer, Google Chrome, Mozilla Firefox, Opera, Safari.

Hyper Text Transfer Protocol (HTTP): HTTP is the set of rules or protocol related to the transfer of Hypertext between two or more computers. The World Wide Web which preserves the vast storage of information is available through HTTP.

Hyper Text Markup Language (HTML): HTML was invented in 1990 by a scientist called Tim Burners-Lee. HTML is the “mother tongue” of browser. The HTML codes are used to create links. These links may be textual or graphical to link another HTML documents, text files, graphics, animation and sound.

Uniform Resource Locator (URL): A URL identifies a particular Internet resource (example a web page, an image or a text file etc.). Every resource available via the World Wide Web has a unique URL. URLs consist of letters, numbers, and punctuation. The basic structure of a URL is: Protocol: / server-name .domain- name. Top-level-domain: port/Directory/filename. Examples are:

Domain Name: A Domain name is a way to identify and locate computers connected to the Internet. A domain name always contains two or more components separated by periods, called “dots”. There are some categories of domain name:

  1. Top-level domain
  2. Second-level and lower level domains

The major categories for top –level domain name are given below:

  1. Organization Domains (Domain: Purpose):
    • com: Commercial entities
    • edu: Educational institutions
    • gov: Govt. institutions
    • int: International institutions
    • net: Network resources
    • org: Organizations
  2. Geographic Domains (Domain: Country):
    • in: India
    • au: Australia
    • ca: Canada
    • dk: Denmark
    • fr: France
    • uk: United Kingdom
    • us: United States