The Big Story
The Internet
- a gigantic collection of millions
of computers, all linked together on a computer network.
- this network allows all of the computers
to communicate with one another
- a home computer may be linked to the
Internet using a phone-line modem, DSL or cable modem that talks
to an ISP (Internet Service
Provider). A computer in a business or university
will usually have a NIC (Network
Interface Card) that directly
connects it to a LAN (Local
Area Network) inside the business.
The business can then connect its LAN to an ISP using a high-speed
phone line like a T1 line. A T1 line can handle approximately
1.5 million bits per second, while a normal phone line using a
modem can typically handle 30,000 to 50,000 bits per second (28k
or 56k modems are the most popular).
- ISPs then connect to larger ISPs, and
the largest ISPs maintain fiber-optic "backbones" for
an entire nation or region. Backbones around the world are connected
through fiber-optic lines, undersea cables or satellite links.
In this way, every computer on the Internet is connected to every
other computer on the Internet.
- To keep all of these machines straight,
each machine on the Internet is assigned a unique address
called an IP address (Internet
Protocol).
The World Wide Web
- the World Wide Web allows rich and diverse
communication by displaying text, graphics, animations, photos,
sounds and video.
- physically consisits of your personal
computer, web browser software, a connection to an Internet service
provider, computers called servers that host digital data, and
routers and switches to direct the flow of information.
- known as a client-server system. Your
computer is the client; the remote computers that store electronic
files are the servers.
- here's how it works: First you
enter the URL (Universal Resource Locator) of
the website in your web browser. Then your browser requests
the web page from the web server. The server
sends the data over the Internet to your computer. Your
web browser interprets the data, displaying
it on your computer screen.
- the "glue" that holds the Web
together are called hyperlinks. This feature allows electronic
files on the Web to be linked so you can jump easily between them.
- on the Web, you navigate through pages
of information based on what interests you at that particular
moment, commonly known as browsing or surfing the Net.
- to access the Web you need a web browser,
such as Netscape Navigator or Microsoft Internet Explorer.
- web pages are written in a computer
language called HTML (Hypertext
Markup Language).
Browsers
- plug-ins are used to enhance websites
both visually and structurely.
- the most popular plug-in
is Macromedia's Flash Player. No other plug-in
has stormed the web market so quickly and remained on top. It
is probably its appeal to web designers as well as web programmers
that has allowed it to become such a powerhouse in the industry.
- the most popular Web browsers
are Microsoft Internet Exporer for PC computers and Apple Safari for Mac computers.
- There is also an open source browser called Firefox that is making waves in the browser wars.
Servers
- a server is nothing more than a regular
computer running special software that is used to interact with
a client. You can turn your home computer into a server if you
wanted to, in fact chances are it already has that capability
built in!
- it is possible and common for a machine
to be both a server and a client, but that will not apply to this
courses studies.
- There are four major types of
servers: HTTP (Hypertext
Transfer Protocol), FTP
(File Transfer Protocol)
and DNS (Domain
Name Server), Email
(Electronic mail).
- you are probably most familiar with an
Email server. It allows you to send and receive messages from
your own email address to/from anyone else with an email address
in the entire world. It is usually its own server due to the large
amounts of daily volume it may have to process.
- an FTP server is used to transfer files
from a client computer to the server computer. It is often used
in conjunction with an HTTP server.
- Because most people have trouble remembering
the strings of numbers that make up, and because IP addresses
sometimes need to change, all servers on the Internet also have
human-readable names, called domain names. A
DNS server keeps track of what IP addresses domain names need
to point to.
- an HTTP server is the backbone of the
World Wide Web. It allows multiple domains to physically exist
on one server through the process called virtual hosting.
When you go to a website and input something like http://www.google.com,
you are literally calling the HTTP server and saying "hello,
anyone home at this address?". The http server then answers
you with a "yes we are" (showing you the page) or "no,
not right now" (displaying an annoying 404 not found page).
- in the "web design world" you
will most likely deal with ftp servers the most. Generally mail,
http, and dns servers are left for the System or Network Administrators
to take care of.