Module 4: Internet & E-mail

Module 4: Internet & E-mail

• The Internet is a global network connecting computers and devices. It enables information sharing through services like email, web browsing, and file sharing.

Brief Idea & History

• The Internet's foundation was laid in the 1960s with ARPANET (Advanced Research Projects Agency Network).
• ARPANET was designed to share computer resources across long distances.
• In 1969, ARPANET connected four major universities in the US.

1970s - Birth of TCP/IP

• TCP/IP (Transmission Control Protocol/Internet Protocol) became the standard communication protocol.
• It allowed different networks to interconnect.
• ARPANET connected to European networks in 1973.

1980s - Domain Name System (DNS) and Growth

• The Domain Name System (DNS) was introduced in 1983.
• It allowed easier identification of websites using names instead of numerical addresses.
• Universities and research institutions connected to ARPANET.

1990s - The World Wide Web (WWW)

• Tim Berners-Lee invented the World Wide Web in 1991.
• WWW revolutionized internet access of information.
• Web browsers like Netscape and Mosaic were developed.
• Internet became more accessible.
• Commercialized in the mid-1990s with wide business and individual use.

2000s to Present - Expansion and Modern Internet

• Broadband connections, wireless networks, and mobile devices integrated the internet into daily life.
• Web 2.0 emerged, focusing on user-generated content, social media, and interactive platforms like Facebook and YouTube.
• Today, the Internet powers communication, entertainment, business, and the Internet of Things (IoT).

Network Devices

• Router: Directs data packets between networks, ensuring correct destination. Connects local and wider networks.
• Switch: Connects devices within a local area network (LAN), forwarding data to the correct device at the data link layer.
• Hub: A basic networking device that broadcasts data to all connected devices. Less efficient than a switch.
• Modem: Converts between digital and analog signals, enabling device connection to the internet through telephone or cable systems.
• Access Point (AP): Enables wireless devices to connect to a network creating a Wireless Local Area Network (WLAN) - often used in Wi-Fi networks.
• Firewall: A security device that controls incoming and outgoing network traffic based on security rules. It helps protect a network from unauthorized access.

Protocols

• TCP/IP (Transmission Control Protocol/Internet Protocol): Foundational suite of protocols for the internet. TCP ensures reliable data transfer, while IP handles packet routing.
• HTTP/HTTPS (Hypertext Transfer Protocol/Secure): Used to transfer web pages. HTTPS is a secure version, encrypting data.
• FTP (File Transfer Protocol): Transfers files between a client and a server. Commonly used for uploading and downloading files.
• SMTP (Simple Mail Transfer Protocol): Used for sending emails between servers. Ensures reliable email delivery.
• POP3 (Post Office Protocol version 3): Used to download emails from a server. Typically removes emails after downloading.
• IMAP (Internet Message Access Protocol): Used to retrieve emails while keeping them on the server, enabling access from multiple devices and synchronization.
• DHCP (Dynamic Host Configuration Protocol): Automatically assigns IP addresses to devices on a network. Eliminates manual configuration needs.
• DNS (Domain Name System): Translates human-readable domain names into IP addresses. Allows users to access websites by easy-to-remember names.
• SSH (Secure Shell): A protocol used to securely connect to remote devices over an encrypted connection for remote server administration.

Web Browser

• Software application to access, retrieve, and view internet information. Acts as a gateway to the World Wide Web. Interprets and displays web pages, multimedia, and other resources.
• Common features include: address bar, navigation buttons (back, forward, refresh, home), bookmarks, tabs, and download manager. Security features such as private browsing mode.

Email (Electronic Mail)

• Method of exchanging digital messages over the internet. Widely used communication tool.
• Components:
  • Email Address: Unique identifier (e.g., [email protected]).
  • Username: Identifier for user or entity (e.g., john.doe).
  • Domain: Server hosting email service (e.g., gmail.com, outlook.com)
• Email Parts:
  • Subject Line: Brief description of content.
  • Body: Main email content (text, images, hyperlinks).
  • Attachments: Files sent with email.
  • CC (Carbon Copy): Sends a copy of the email.
  • BCC (Blind Carbon Copy): Sends a copy without revealing recipient email addresses.
• Working Procedure:
  • Composing and Sending: User composes email in client software, clicks 'send' and connects to sender's SMTP server.
  • Email Transmission: Email forwarded to recipient's mail transfer agent (MTA).
  • Email Reception: Email stored on recipient's server until retrieved. Recipient retrieves using protocols like POP3(downloads and deletes from server) or IMAP (synchronizes between devices).
  • Reading: Recipient accesses email server. The email client displays the email(retrieving through IMAP or POP3).