Networks
The Internet consists of the entire global network of computers. This network is made works on theclient/server model. Client/Server can describe a relationship between two computer programs. The clientcomputer requests some type of service (such as a file or database access) from the server. The servercomputer fulfills the request and transmits the results to the client over a network.
Peer-to-peer-network is a type of decentralized network where each computer on the network (peers) acts both as a client and server.
When a client computer makes a request to the server, the requested files are copied from the server to the client, this is known as downloading. The process of the page appearing in the web browser is called loading.s
Data on a network travels through what is called communication circuits. The amount of data that can be transmitted at any one time through a communication circuit is called bandwidth. Bandwidth is measured inbits.
Bits and Bytes – Computers are based on a Binary is a numbering system, consisting of two unique numbers 0 and 1. A bit is a single binary digit. A byte is made up of 8 bits.
In order to connect to any type of network a computer must have a network interface card (NIC) or network card. A cable is then run from the NIC to the server or another client computer.
In a large network a special device is used to connect the computers on the network.
There are several different types of devices used to complete this task each one has special capabilities.
- Hubs allow for multiple computers to talk to each other all at the same time.
- Switches are like traffic lights allowing one computer to talk another, one at a time.
- Routers are like switches, but also direct the data allowing for Internet connections.
There are different types of networks:
- Local Area Network (LAN)
- Wide Area Network (WAN)
Furthermore there are different types of network connections:
- Cable connection
- Wireless connection
Connecting to the Internet
In order to connect to the Internet one must first obtain an Internet service provider (ISP), who allows for access to the network access points (NAPs) to the Internet.
In order for a computer to transmit data over a telephone or cable line, a device known as a modem is required. The modem allows for a connection to your ISP.
Go Wireless! In order to access the Internet wirelessly, a WLAN (wireless LAN) card is required and can be used in place of a NIC card. Note that a WLAN card requires that the computer accessing the network be within the range of a wireless access point.
Once connect to the Internet one can access the World Wide Web or web. The web is the part of the Internetthat is available to the public and is made up of a network of connected computers called web severs.
The web is made up of hypertext documents. Hypertext refers to text displayed on an electronic device with a reference (hyperlink) to another document that can be instantly accessed. The concept of linked hypertext is the defining foundation for the web and was conceived by Tim Berners-Lee at the CERN, the European Organization for Nuclear Research.
In 1989, Berners-Lee would make available on the Internet, the code for a hypertext server program. This program would later be installed on web (hypertext) servers and used to store files in hypertext markup language (HTML).
Since that time HTML has become the standard language for developing hypertext documents or web pages. A website is a group of related web pages, which all reside on the same web server. The homepage is the first page that displays when visiting a specific website.
In order to access information on a web server, Berners-Lee developed the Hypertext Transfer Protocol (HTTP) a set of rules for exchanging files such as text, graphics/images, sound, video and other media via the web.
When a client computer sends a request it must identify a resource on the Internet or uniform resource identifier (URI) The URI is made up of two distinct parts the universal resource name (URN) and theuniversal resource locator (URL). Think of it like this, the URI is specific persons information in a contact book, the URN is the person’s name while the URL is the person’s address.
Thus, just as people have addresses to locate their homes, each web server on the Internet is given their ownInternet Protocol (IP) address. An IP address is made up of a set of four groups of numbers called octets.
Since it is difficult to remember large groups of numbers the Domain Name System (DNS) was established and Associates text-based domain names with numeric IP address assigned to a device.
A top-level domain (TLD) refers to the last part of a domain name. A TLD refers to the top-level in the DNS hierarchy and identifies the website through association. The ICANN directs the designated organizations in the management of each separate TLD registry. Common TLD’s include:
- .com
- .org
- .net
- .gov
- .edu
- .us (or other country code)
Therefore in order to access the Internet one must know the URL of the web page or site you are trying to access. The URL consists of the specific protocols for communication transfer, the name of the web server the data is located on, and the domain name or IP Address. One example is http://wwww.getcereativetoday.com , HTTP is the protocol, www is the web server and getcreativetoday.comis the domain name.
Web Browsers
Web pages are documents written in HTML. HTML is made elements (tags) and attributes that define how and what content a web page displays. In order to display this content a special software called a web browseris required. A web browser translates HTML coding to display in a meaningful manner, with text, graphics,hyperlinks and more.