Transmission Control Protocol / Internet Protocol.

TCP/IP decides the rules every computer needs to follow to be able to communicate with other computers. It states how computers transfer data amongst each other and how computers should be connected to the internet.

TCP/IP uses several protocols to do this.

1. TCP (Transmission Control Protocol) this allows applications to communicate with each other.
2. IP (Internet Protocol) this allows computers to communicate with each other.
3. UDP (User Datagram Protocol) this takes care of simple communication between applications.
4. DHCP (Dynamic Host Configuration Protocol) takes care of dynamic addressing
5. ICMP (Internet Control Message Protocol) is used for errors and statistics
   

TCP
TCP allows applications to communicate. It does this by allowing one application to send a request to the other (this request needs to be send to the exact location). It then expects a handshake. When it succeeds it will create a "full-duplex" (this allows communication in both directions) communication between the 2 applications until one of them is closed.
More on TCP.

IP
IP takes care of the addressing. Meaning IP is used to make sure the parts of your package with information arrive at the right location. It does this by letting IP routers decide the road a package will take to get to it's destination (this can be a different road every time).

Think of having 2 pots with a tube between them. In one of them you have some water. Then you start to heat up the water. All molecules will travel a different road trough the tube however all come together again as the liquid in the other pot.
More on IP.

TCP and IP united.
As you can see TCP and IP together results in a powerful protocol. In which TCP takes care of breaking apart the packages to be send and the reassembling of them while IP takes care of the addressing.

IP addresses.
Before you are able to communicate over the internet just like receiving letters in real life you will need to have an address. Not having one would result in your mailman not knowing what mailbox is yours. For that IP uses 32-bits addressing meaning a combination of 4 numbers between 0 and 255 which are unique for every computer.

Domain names.
Domain Name Servers you will have a lot of contact with when you are trying to find out information about a certain website. Because it is kind of hard for us humans to remember 4 numbers (at least i you have more then one of those strings) we decided we would place a link between a name and those numbers to make it more easy. Because of this DNS servers all over the world get updated when a new domain is registered and taken in use.

Just think of DNS servers as phone books that work the other way around. You got a persons phone number and now you want to know what number belongs to that name.

More then just TCP and IP.
TCP/IP uses several other protocols to complete itself however they are all based upon TCP or IP, these are:

HTTP - Hyper Text Transfer Protocol
This protocol takes care of the communication between a server and a browser.
HTTPS - Secure HTTP
HTTPS does the same as HTTP but does this in a more secure way.
SSL - Secure Sockets Layer
This protocol is used to encrypt data.
SMTP - Simple Mail Transfer Protocol
Is used for sending e-mails.
MIME - Multi-purpose Internet Mail Extensions
Allows the SMTP protocol to send binary data and multimedia.
IMAP - Internet Message Access Protocol
Used to retrieve and store mail.
POP - Post Office Protocol
Used to download mail from a server to your computer.
FTP - File Transfer Protocol
Allows transferring of files between computers.
NTP - Network Time Protocol
Used to make sure the clocks of two computers run similar.
DHCP - Dynamic Host Configuration Protocol
Used to allocate dynamic IP addresses to computers.
SNMP - Simple Network Management Protocol
Used to administrate computer networks.
LDAP - Lightweight Directory Access Protocol
Is used to collect information on users and mail addresses.
ICMP - Internet Control Message Protocol
Takes care of error handling on the network.
ARP - Address Resolution Protocol
Used to find the hardware address of a computer network card.
RARP - Reverse Address Resolution Protocol
Used to find out what the IP address of a computer is based in the address of the computers network card.
BOOTP - Boot Protocol
Used for booting computers from a network.
PPTP - Point to Point Tunneling Protocol
Used for setting up connections between two or more private networks.

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