Transcript Computers in Society

Computers in Society
Week 3:
The Internet
Preliminaries
There are two important things to know before we
talk about the internet:
• Packet switching
• Standards
Circuit Switching
Older telephone networks were based on circuit switching,
which sets up a dedicated circuit for a communications.
Packet Switching
Packet switching breaks messages into pieces, which can be
routed through the network on different paths. The pieces
(packets) are reassembled in order at the receiving computer
(host).
Standards
Technical standards are agreements that specify
details of how components or systems are
manufactured, behave, or interact. For example,
the IEEE has issued a number of standards for buses
that connect computer hardware. Conforming to
these standards allows manufacturers to build
computer cards that can be plugged into almost any
computer.
Standards (2)
Protocols are standards for how systems
communicate with each other.
The internet depends on the TCP/IP standards.
Following these standards allows any host on the
internet to communicate with any other host on the
internet.
Without such universal agreement, we’d have many
little networks.
An important point: the word internet is
composed of two parts:
• inter, which means between.
• net, which is short for network.
The internet connects many smaller networks
(such as the Bucknell campus network) into a
much larger network.
Early Internet History
The history of the internet starts back in the early
1960’s, when researchers at different universities
and government laboratories wanted to allow their
new computers communicate with each other.
J.C.R. Licklider wrote his ideas for creating a
distributed network that were developed into a
network called the ARPANET.
Early Internet History (2)
Other researchers at other facilities were developing
computer networks as well. In general these
networks could not communicate with each other.
Early Internet History (3)
Email was introduced in 1965. Initially email users
had to be on the same system. The ARPANET
improved email by allowing users on different
systems to communicate.
To email someone on a different system, you had to
know which computers were connected to which
other computers, and to specify a route in the
address. For example, an email address might look
like this:
myhost!nethost!farhost!user@hishost
Early Internet History (4)
In the 1970’s the Unix system was invented and spread to
many universities and research labs. Unix had a UUCP (Unixto-Unix copy) capability that allowed Unix systems to call
each other over telephone lines and transfer files.
In 1979 Tom Truscott and Jim Ellis designed the Usenet
network to transfer email and bulletin board messages using
UUCP. It was a distributed network and content was not
centralized. It was the start of recreational use of the
internet.
TCP/IP
In 1982 the Internet Protocol Suite (TCP/IP) was
standardized.
•IP (Internet Protocol) specified the way to
communicate between (local) networks.
•TCP (Transmission Control Protocol) specified how
hosts (computers) would communicate with each
other over the internet.
This laid the foundation for today’s internet.
The World-Wide Web
The next important step in the development of the
internet as we know it was the creation of the
world-wide web (www) by Tim Berners-Lee at CERN.
In late 1990/early 1991 Berners-Lee developed a
network-based implementation of hypertext, text
that includes links to other text pages. This is the
foundation of web pages.
The World-Wide Web (2)
In addition to the hypertext implementation,
Berners-Lee developed a protocol for transferring
hypertext across a network (HTTP, the HyperText
Transfer Protocol) and a web browser for viewing
the hypertext.
The world-wide web began to spread to other
universities and research labs.
The World-Wide Web (3)
In 1993 a group at the University of Illinois at UrbanaChampaign (UIUC) led by Marc Andreessen developed the
Mosaic web browser.
Mosaic had a graphical user interface. Most previous
internet interfaces were text-based. Mosaic became very
popular as a result. It led to the development in 1994 of the
Netscape Navigator browser, which soon became the most
popular browser in the world. Netscape could run on PCs,
which introduced the web to the population outside
laboratories and universities.
The Internet as We Know It
By 1995 all the pieces were in place for the
development of the internet as we know it. Access
speeds were slow, so the content was limited to
what could be transmitted at the slow speeds, but
the basic capabilities were there.
The new internet users began to use it for a range of
new purposes. I will talk about three early
developments: email, shopping, and pornography.
Email
As the internet became popular, more and more
people began to use email. Email had major
benefits because it made communication fast and
inexpensive. However, it had two negative effects:
• People began to send unsolicited messages (spam)
trying to sell products or even in some cases trying
to steal money.
• People used email instead of writing letters, and
postal business began to decrease.
Internet Commerce
People also began shopping on the web.
Amazon.com went on line in 1995 selling only
books. Ebay went on line in 1995.
Internet shopping makes life more convenient for
shoppers. However, it led to lower sales for socalled brick-and-mortar stores. In the US, first small
independent bookstores went out of business, and
now large bookstore chains are doing poorly.
Pornography
The internet quickly developed a large pornography
industry. The pornography industry has some very
negative social consequences: It has close ties with
organized crime, and it exploits people in highly
damaging ways.
However, because of the needs of this industry and
the willingness of many people to pay for it, the
pornography industry helped drive the development
of many internet technologies.
Pornography (2)
Pornographers were among the first to use
streaming video, live webcams, and secure
payment systems.
"Nonetheless, it is clear that much of the
popular technology of multimedia has been
driven by the adult entertainment industry.”
The Internet Encyclopedia, Volume 1, Hossein
Bidgoli (Wiley)