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Email Protocols – Complete Important Table

Protocol	Full Form	Port Number	Main Function
SMTP	Simple Mail Transfer Protocol	25	Sending emails
SMTP Submission	Simple Mail Transfer Protocol	587	Sending emails securely
SMTPS	Simple Mail Transfer Protocol over TLS	465	Secure email sending
POP3	Post Office Protocol Version 3	110	Receiving / downloading emails
POP3S	Post Office Protocol Version 3 over SSL/TLS	995	Secure email receiving
IMAP	Internet Message Access Protocol	143	Receiving and managing emails
IMAPS	Internet Message Access Protocol over SSL/TLS	993	Secure email access and synchronization
MIME	Multipurpose Internet Mail Extensions	No dedicated port	Email attachments, images and multimedia
HTTP	Hypertext Transfer Protocol	80	Accessing webmail
HTTPS	Hypertext Transfer Protocol Secure	443	Secure access to webmail
DNS	Domain Name System	53	Resolves domain names and finds mail servers through MX records
TLS	Transport Layer Security	No dedicated port	Secures email communication
FTP	File Transfer Protocol	20, 21	File transfer (not an email protocol)

Email History & General Knowledge

Topic	Important Information
Inventor of Email	Ray Tomlinson
Year of Email Invention	1971
First Network Used	ARPANET
Email Symbol	@
Father of Email	Ray Tomlinson
Gmail Founder / Creator	Paul Buchheit
Gmail Launch Year – Yahoo Mail Launch Year	2004 – 1997
Hotmail Founders	Sabeer Bhatia and Jack Smith
Hotmail Launch Year	1996
CC	Carbon Copy
BCC	Blind Carbon Copy
RFC	Request for Comments
MIME	Email attachments and multimedia
MX Record	Mail Exchange Record
Email Communication	Asynchronous

Exam priority: SMTP (25), POP3 (110), IMAP (143), SMTP (587), POP3S (995), IMAPS (993), MIME, Ray Tomlinson (1971).

1. Internet & WWW – Important History

Topic	Important Information
Internet	Interconnected global network of computers
Father of the Internet	Vint Cerf and Bob Kahn
Inventor of World Wide Web (WWW)	Tim Berners-Lee
Year WWW was invented	1989
WWW became publicly available	1991
First website	info.cern.ch
First web browser	WorldWideWeb (later called Nexus)
First graphical web browser	Mosaic
Mosaic launch year	1993
First search engine	Archie (1990)
First web search engine	Wandex (1993)
ARPANET	Advanced Research Projects Agency Network
ARPANET started	1969
First ARPANET message	LO (intended to be LOGIN)
TCP/IP adopted by ARPANET	1983
Internet Protocol Suite	TCP/IP
DNS introduced	1983
Father of WWW	Tim Berners-Lee
URL	Uniform Resource Locator
URI	Uniform Resource Identifier
ISP	Internet Service Provider

2. Internet Protocols & Port Numbers

Protocol / Term	Full Form	Port Number	Main Function
HTTP	Hypertext Transfer Protocol	80	Transfers web pages
HTTPS	Hypertext Transfer Protocol Secure	443	Secure transfer of web pages
FTP	File Transfer Protocol	20, 21	Transfers files
FTPS	File Transfer Protocol Secure	990 (implicit TLS)	Secure file transfer
SFTP	SSH File Transfer Protocol	22	Secure file transfer
SSH	Secure Shell	22	Secure remote computer access
Telnet	Teletype Network	23	Remote computer access (unencrypted)
DNS	Domain Name System	53	Converts domain names into IP addresses
DHCP	Dynamic Host Configuration Protocol	67, 68	Automatically assigns IP addresses
TCP	Transmission Control Protocol	No fixed port	Reliable data transmission
UDP	User Datagram Protocol	No fixed port	Fast, connectionless data transmission
IP	Internet Protocol	No fixed port	Addressing and routing data packets
ICMP	Internet Control Message Protocol	No port	Network error reporting and diagnostics
POP3	Post Office Protocol Version 3	110	Receives emails
IMAP	Internet Message Access Protocol	143	Accesses and synchronizes emails
SMTP	Simple Mail Transfer Protocol	25, 587	Sends emails
NTP	Network Time Protocol	123	Synchronizes computer clocks
SNMP	Simple Network Management Protocol	161, 162	Monitors and manages network devices
LDAP	Lightweight Directory Access Protocol	389	Accesses directory services
LDAPS	Lightweight Directory Access Protocol over TLS	636	Secure directory services
RDP	Remote Desktop Protocol	3389	Remote desktop access

3. Internet & WWW – Important Terms

Term	Full Form / Meaning	Main Function
WWW	World Wide Web	Collection of interconnected web pages
Internet	Interconnected Network	Global network of connected computers
URL	Uniform Resource Locator	Address of a web resource
URI	Uniform Resource Identifier	Identifies a resource
IP	Internet Protocol	Provides addressing and routing
IPv4	Internet Protocol Version 4	Uses 32-bit IP addresses
IPv6	Internet Protocol Version 6	Uses 128-bit IP addresses
ISP	Internet Service Provider	Provides Internet access
HTML	Hypertext Markup Language	Creates web pages
CSS	Cascading Style Sheets	Styles web pages
XML	Extensible Markup Language	Stores and transports structured data
JavaScript	JavaScript	Adds interactivity to websites
Web Browser	Software to access websites	Opens and displays web pages
Search Engine	Online search service	Finds information on the Internet
Web Server	Server software/computer	Hosts and delivers web content
Homepage	Main page of a website	Starting page of a website
Hyperlink	Clickable link	Connects web pages or resources
Domain Name	Human-readable website address	Identifies a website
IP Address	Internet Protocol Address	Identifies a device on a network
Cookie	Small data stored by a browser	Remembers website information
Cache	Temporary stored data	Speeds up loading
Bandwidth	Data transmission capacity	Measures network capacity
Download	Receiving data	Transfers data from a server to a device
Upload	Sending data	Transfers data from a device to a server
VPN	Virtual Private Network	Creates an encrypted network connection
LAN	Local Area Network	Connects devices in a limited area
WAN	Wide Area Network	Connects networks over large distances
MAN	Metropolitan Area Network	Covers a city or metropolitan area
WLAN	Wireless Local Area Network	Provides wireless local networking
Intranet	Private organizational network	Internal communication
Extranet	Controlled private network access	Shares resources with authorized outsiders

4. Famous Founders, Inventors & Launch Years

Person / Organization	Invention / Contribution	Year
Vint Cerf & Bob Kahn	TCP/IP development	1970s
Tim Berners-Lee	World Wide Web	1989
Tim Berners-Lee	First website	1991
Tim Berners-Lee	HTML, HTTP and URL development	Early 1990s
Ray Tomlinson	Network Email	1971
Donald Davies	Packet Switching concept	1960s
Paul Baran	Packet Switching research	1960s
Leonard Kleinrock	Packet Switching research	1960s
ARPA	Established ARPANET project	1969
Jon Postel	Important Internet standards contributions	—
Marc Andreessen & Eric Bina	Mosaic Browser	1993

5. Famous Web Browsers & Search Engines

Name	Founder / Company	Launch Year
Google Chrome	Google	2008
Mozilla Firefox	Mozilla	2004
Internet Explorer	Microsoft	1995
Microsoft Edge	Microsoft	2015
Safari	Apple	2003
Opera	Opera Software	1995
Netscape Navigator	Netscape	1994
Mosaic	NCSA	1993
Google Search	Larry Page & Sergey Brin	1998
Yahoo!	Jerry Yang & David Filo	1994
Bing	Microsoft	2009
Yahoo Mail	Digital Equipment Corporation	1997
DuckDuckGo	Gabriel Weinberg	2008

6. Important Internet Abbreviations

Abbreviation	Full Form
WWW	World Wide Web
HTTP	Hypertext Transfer Protocol
HTTPS	Hypertext Transfer Protocol Secure
HTML	Hypertext Markup Language
URL	Uniform Resource Locator
ISP	Internet Service Provider
IP	Internet Protocol
TCP	Transmission Control Protocol
UDP	User Datagram Protocol
DNS	Domain Name System
FTP	File Transfer Protocol
VPN	Virtual Private Network
LAN	Local Area Network
WAN	Wide Area Network
MAN	Metropolitan Area Network
WLAN	Wireless Local Area Network
Wi-Fi	Wireless networking technology (not an official acronym)
VoIP	Voice over Internet Protocol
WWW	World Wide Web
CAPTCHA	Completely Automated Public Turing test to tell Computers and Humans Apart
ARPANET	Advanced Research Projects Agency Network
TCP/IP	Transmission Control Protocol / Internet Protocol
ISP	Internet Service Provider

7. Important Differences for Exams

Internet	WWW
Global network infrastructure	Service that operates over the Internet
Connects computers and networks	Connects web pages and resources
Developed through multiple technologies	Invented by Tim Berners-Lee
Uses TCP/IP	Uses HTTP/HTTPS

HTTP	HTTPS
Not encrypted by default	Encrypted using TLS
Port 80	Port 443
Less secure	More secure
Used for web communication	Used for secure web communication

Important facts to memorize:

1. Father of Internet: Vint Cerf and Bob Kahn.
2. Father of WWW: Tim Berners-Lee.
3. HTTP: Port 80.
4. HTTPS: Port 443.
5. FTP: Ports 20 and 21.
6. DNS: Port 53.
7. SSH: Port 22.
8. Telnet: Port 23.
9. TCP/IP: Main Internet protocol suite.
10. First website: info.cern.ch.
11. ARPANET: Started in 1969.
12. IPv4: 32 bits.
13. IPv6: 128 bits.
14. HTML: Used to create web pages.
15. Google: Founded by Larry Page and Sergey Brin.