TCP/IP Revised

Easy definition and basic intro to TCP/IP (courtesy w3schools.com)

• TCP is for communication between applications. A communication link is established between the applications through a handshake and it persists until one of them closes it.
• IP is for communication between computers. IP is a "connection-less" communication protocol. With IP, messages (or other data) are broken up into small independent "packets" and sent between computers via the Internet. IP is responsible for "routing" each packet to the correct destination.
• When an IP packet is sent from a computer, it arrives at an IP router. The IP router is responsible for "routing" the packet to the correct destination, directly or via another router. The path the packet will follow might be different from other packets of the same communication. The router is responsible for the right addressing, depending on traffic volume, errors in the network, or other parameters.
• TCP is responsible for breaking data down into IP packets before they are sent, and for assembling the packets when they arrive. IP is responsible for sending the packets to the correct destination.
• All over the world, DNS servers are connected to the Internet. DNS servers are responsible for translating domain names into TCP/IP addresses.
• HTTP takes care of the communication between a web server and a web browser.
• HTTPS takes care of secure communication between a web server and a web browser.
• The SSL protocol is used for encryption of data for secure data transmission.
• SMTP is used for transmission of e-mails. SMTP can only transmit pure text. It cannot transmit binary data like pictures, sounds or movies.
• The MIME (Multipurpose Internet Mail Extensions) protocol lets SMTP transmit multimedia files including voice, audio, and binary data across TCP/IP networks.
• POP (Post Office Protocol) is used for downloading e-mails from an e-mail server to a personal computer. If your email program uses POP, all your emails are downloaded to your email program (also called email client), each time it connects to your email server.
• IMAP (Internet Message Access Protocol) is used for storing and retrieving e-mails. The main difference between the IMAP protocol and the POP protocol is that the IMAP protocol will not automatically download all your emails each time your email program connects to your email server. The IMAP protocol allows you to look through your email messages at the email server before you download them. With IMAP you can choose to download your messages or just delete them. This way IMAP is perfect if you need to connect to your email server from different locations, but only want to download your messages when you are back in your office.
• FTP takes care of transmission of files between computers.
• NTP (Network Time Protocol) is used to synchronize the time (the clock) between computers.
• DHCP is used for allocation of dynamic IP addresses to computers in a network.
• SNMP (Simple Network Management Protocol) is used for administration of computer networks.
• LDAP (Lightweight Directory Access Protocol) is used for collecting information about users and e-mail addresses from the internet.
• ICMP (Internet Control Message Protocol) takes care of error-handling in the network.
• ARP (Address Resolution Protocol) is used by IP to find the hardware address of a computer network card based on the IP address.
• RARP is used by IP to find the IP address based on the hardware address of a computer network card.
• BOOTP is used for booting (starting) computers from the network.
• PPTP (Point to Point Tunneling Protocol) is used for setting up a connection (tunnel) between private networks.