Internet Concepts

The Internet is a worldwide network of thousands of interconnected computer networks. The Internet was originally funded by the U.S. Defense Advanced Research Projects Agency (DARPA) and was created to help researchers and scientists quickly exchange information. The internet makes it possible for any computer connected to it to send and receive data from any other. Today, users on the Internet can not only transfer files in electronic format, they can send messages via e-mail, conduct research using a variety of resources, hold real-time "talk" sessions both in text and voice with others connected to the Internet, and much more.

Protocol

Protocol is defined as the rules that enable 2 devices to communicate. Since the internet is a network of communicating devices, there are a number of different protocol that need to be discussed to have an understanding of Internet Concepts

TCP/IP Transmission Control Protocol/Internet Protocol is the communication protocol suite that is standard for all Internet-connected machines.

HTTP HyperText Transfer Protocol is the standard protocol for transmitting Web pages on the Internet,while HTTPS is HTTP ver Secure Sockets Layers (SSL). This protocol was developed by Netscape for securing data sent by the browser by means of encryption and enable the secured transmission of Web pages.

There are many different information protocols/services besides HTTP

FTP File Transfer Protocol is the standard protocol for transferring files on the Internet.

SMTP -Simple Mail Transfer Protocol is used for sending electronic mail messages.

NNTP- Network News Transfer Protocol is the predominant protocol used to transfer, distribute, and retrieve news articles across the internet

IP Address

Every machine on the Internet has a unique identifying number, called an IP Address. IP addresses are normally expressed in decimal format as a "dotted decimal number" and typically look like this: 71.224.158.101

World Wide Web is an example of an information protocol/service that can be used to send and receive information over the Internet. It is an example of an information protocol/service that works using a Client/Server software design. Therefore it requires two pieces of software to work: Client software which you use to request information, and Server software which an Information Provider uses to answer requests and provide their information. Most Internet information protocol/services are designed this way.

ISP: Internet Service Provider

The first step in "connecting" to the internet is to obtain an ISP which stands for Internet Service Provider. These are fee-based businesses that provides an individual with access to the internet. Initially Point to Point Protocol (PPP) was the protocol used for sending information via a modem which is connected to the Internet (commonly known as dial-up access). Today cable, or high-speed DSL circuit allows for more information to be transfered more quickly.

You can not "surf the net" with an ISP alone. A Web Browser (such as Netscape, Internet Explorer, or Firefox) is required to view web pages.  A browser is software that goes out and retrieves web pages that are displayed on the computer screen.  Web pages present differently depending on what browser is being used.

Accessing a web page

Information on the Web is displayed in pages which are written in a standard language called HTML (HyperText Markup Language). Web sites and the pages they contain each have a unique worldwide address or Uniform Resource Locator (URL). To make it easeire to access a webpage, rather than keying in an IP address, a user keys in a domain name or common name (such as www.umasd.org). A "DNS Server" then translates the friendly "domain name" URLs to dotted decimal IP addresses as discussed above. If a user incorrectly keys in the domain name, then the correct IP address cannot be located, thereby resulting in error messages of an incorrect link.

All of this sending and retrieving takes a lot of work and memory. To save on the "work", your computer relies on cache memory, a fast storage buffer in the central processing unit of a computer. Any web pages you request are stored in your computer's cache. This enables your PC to display these pages to you quickly without having to go back through the Internet to retrieve the page. In a network, there is often a server dedicated to cache sites so that multiple computers do not have to do the work multiple times.

There are certain file extensions that can only be accessed if the computer which is accessing the information has the correct plug-ins to read the information.Plug-Ins are software that integrates sound and video and other capabilities into a web browser for example, in order to view a PDF file, the Adobe Acrobat Reader® plug-in is required. Plug-ins are required for many of the rich multimedia applications on the internet.