Useful Definitions

Packets - part of a large piece of information
             - Contains three parts - Header - Senders IP Address
                                                              - Recievers IP Address
                                                              - Protocal (HTTP)
                                                              - Packet Number
                                               - Payload - The Actual Data
                                               - Trailer - Data to show the end of the Packet
                                                            - Error Corrections

Router - a specialised piece of computer equipment which recieves and sends packets, the router recieves the packet and then forwards them onto the right computer.

Domain Name - Easily Recognised and easy to remember
                       - Example - www.google.com

Protocol - Specifies what path the computer should follow to access the requested file.
Domain - Points to the website where the file is.
Path - The route the internet takes to get to the file being requested.
File Name - The name of the file.

IP Address - a unique number allocated to every computer
                  - Made up of 4 sets of 3 digit numbers (86.134.238.10)

Domain Name Server (DNS) - Translates IP addresses into recognizable domains.

Internet Registries and Registras - Registries - Number
                                                 - Registras - Name
                                                 - Manages IP Addresses and Domain Names

Internet Service Provider (ISP) - Provides an entrance to the internet.

Intranet - a closed off portion of the internet within a single location for example within a business.
Extranet - a piece of an organisations intranet which has been made securely available to other oganisations or individuals.

Clients - Main job is to recieve information. It is a computer on a network using resources provided by the server.
Servers - Main job is to send information. It is a computer on a network that provides resources for clients.

URI - Uniform Resource Identifier - Provides a unique ID
URN - Unique Resource Name - The unique name for something e.g. isbn numbers.
URL - Uniform Resource Locator - Unique location of something e.g. website address.

Program Control Unit (PCU) - Fetches programs from memory and executes them one at a time.
Arithmetic and Logic Unit (ALU) - Performs logical operations when instructed by programs.
Registers - Fast memory locations within the processor.
System Clock - Sends out ticks to sync the operation of the components (measured in GHz)
Internal Bus - Buses within the processor which alllow the PCU & ALU to communicate.
Dedicated Registers - Assigned a specific purpose by the designer of the processor.
General Purpose Register - Available for the programmer to store data temporarily.
Accumulator (ACC) - Holds the result of calculations.