2. Contents:
• Information retrieval
• Search engines
• Finding people on the Internet
• Chat
• Uploading and downloading files
• Telnet
• Blogs
• Newsgroups
• E-Mail
• Other Internet services
3. Information retrieval
• Information retrieval (IR) is the activity of obtaining information resources relevant
to an information need from a collection of information resources. Searches can
be based on metadata or on full-text (or other content-based) indexing.
• Automated information retrieval systems are used to reduce what has been called
"information overload". Many universities and public libraries use IR systems to
provide access to books, journals and other documents. Web search engines are
the most visible IR applications.
• An information retrieval process begins when a user enters a query into the
system. Queries are formal statements of information needs, for example search
strings in web search engines. In information retrieval a query does not uniquely
identify a single object in the collection. Instead, several objects may match the
query, perhaps with different degrees of relevancy.
• An object is an entity that is represented by information in a database. User
queries are matched against the database information. Depending on
the application the data objects may be, for example, text documents,
images, audio, mind maps or videos. Often the documents themselves are not
kept or stored directly in the IR system, but are instead represented in the system
by document surrogates or metadata.
• Most IR systems compute a numeric score on how well each object in the database
matches the query, and rank the objects according to this value. The top ranking
objects are then shown to the user. The process may then be iterated if the user
wishes to refine the query.
4. Search engines
• Search engines are programs that search documents for specified
keywords and returns a list of the documents where the keywords
were found. A search engine is really a general class of programs,
however, the term is often used to specifically describe systems like
Google, Bing and Yahoo! Search that enable users to search for
documents on the World Wide Web.
• Web Search Engines
Typically, Web search engines work by sending out a spider to fetch
as many documents as possible. Another program, called an
indexer, then reads these documents and creates an index based on
the words contained in each document. Each search engine uses
a proprietary algorithm to create its indices such that, ideally, only
meaningful results are returned for each query.
5. Finding people on the Internet
• The Internet does not have a proper service for looking up information about
people on the network as a whole, although a few attempts at registries have
sprung up. Even if you know a person's real name and where they work, for
example, you can't go to a central place to look up that person's user name or
email address. However, there are two common services that provide some
information about people, finger and whois.
• The finger service looks up information about a user who has an account on the
machine being queried, whether or not that user is currently logged in to the
machine. This information may include the person's real name, login, phone
number, office location, information about when and where they most recently
logged in, and a brief message specified by the user.
• You don't need to know the user name in order to use finger; it will generally give
you information about anybody whose user name or real name contains the string
you specify. If you don't specify a string, it will list information about everybody
currently logged in to the machine being queried. finger can provide invaluable
information to intruders, e.g., by identifying users who rarely log in, or names of
gateway systems. You may wish to block finger requests that come from outside
your internal network, or to supply only minimal information in response to these
requests. finger is legitimately used by plenty of people who are simply trying to
figure out what user name to send mail to, but those people don't need all the
information that finger normally gives out.
6. Chat
• Real-time communication between two users via computer. Once a
chat has been initiated, either user can enter text by typing on the
keyboard and the entered text will appear on the other user's
monitor. Most networks and online services offer a chat feature.
• Chat abbreviation
Used in real-time text-based communications — such as instant
messaging, email, online gaming services, chat rooms, discussion
boards and mobile phone text messaging (SMS) — chat
abbreviations are acronyms and slang terms used to shorten the
amount of text you type when chatting online or on a cell phone.
For example, if you are in a chartroom and someone types a funny
statement, you could answer with LOL (short for Laughing Out
Loud) instead of typing the full phrase out. Chat abbreviations are
used in many different online groups and by people of all ages.
7. Uploading and downloading files
• Upload and download both refer to the file transfer process.
• Upload
To transfer or copy a file or files from your own computer to
another computer. For instance, you might transfer a file from
your home PC to the Yahoo server that stores your Web
Hosting files.
• Download
To transfer or copy a file from another computer to your own.
You might download a file from your Web Hosting account to
your home PC.
8. Telnet
• A terminal emulation program for TCP/IP networks
such as the Internet. The Telnet program runs on your
computer and connects your PC to a server on the
network. You can then enter commands through the
Telnet program and they will be executed as if you
were entering them directly on the server console. This
enables you to control the server and communicate
with other servers on the network. To start a Telnet
session, you must log in to a server by entering a
valid username and password. Telnet is a common way
to remotely control Web servers.
9. Blogs
• A blog is a Web page that serves as a publicly accessible personal journal
for an individual. Typically updated daily, blogs often reflect the
personality of the author.
• The other significant characteristics of today’s blogs are:
- a blog has some form of navigation, usually menus
- a blog’s layout contains a header, footer and content. Usually there is at
least one sidebar running beside the content.
- categories of posts
- that readers can access the archives, previous posts
- that a post can contain text and images, (and often video and other
media)
- that posts can contain links to other posts, both within blog and to the
entire web
- should contain a contact page and form
- should contain an about page
10. Newsgroups
• On the Internet, there are literally thousands of
newsgroups covering every conceivable interest. To
view and post messages to a newsgroup, you need
anew reader, a program that runs on your computer
and connects you to a news server on the Internet.
11. E-Mail
• Short for electronic mail, the transmission of messages over
communications networks. The messages can be notes entered from
the keyboard or electronic files stored on disk. Most mainframes, minicomputers,
and computer networks have an e-mail system. Some electronic-mail systems are
confined to a single computer system or network, but others have gateways to
other computer systems, enabling users to send electronic mail anywhere in the
world. Companies that are fully computerized make extensive use of e-mail
because it is fast, flexible, and reliable.
• Most e-mail systems include a rudimentary text editor for composing messages,
but many allow you to edit your messages using any editor you want. You then
send the message to the recipient by specifying the recipient's address. You can
also send the same message to several users at once. This is called broadcasting.
• Sent messages are stored in electronic mailboxes until the recipient fetches them.
To see if you have any mail, you may have to check your electronic mailbox
periodically, although many systems alert you when mail is received. After reading
your mail, you can store it in a text file, forward it to other users, or delete it.
Copies of memos can be printed out on a printer if you want a paper copy.
12. Other Internet services
• Videoconferencing: Videoconferencing (or video conference)
means to conduct a conference between two or more
participants at different sites by using computer networks to
transmit audio and video data.
• E-learning: Education via the Internet, network, or
standalone computer. e-learning is essentially the network-
enabled transfer of skills and knowledge. e-learning refers to
using electronic applications and processes to learn. e-
learning applications and processes include Web-based
learning, computer-based learning, virtual classrooms and
digital collaboration.
13. • E-banking: a method of banking in which the customer
conducts transactions electronically via the Internet.
• E-shopping: Online shopping (sometimes known as e-tail
from "electronic retail" or e-shopping) is a form of
electronic commerce which allows consumers to directly
buy goods or services from a seller over the Internet using
a web browser.
• E-reservation: E-booking or e-reservation means making
a reservation or appointment for a service via the
internet. The term may also refer to: E-Booking (UK
government project) Computer reservations system
operating via the internet.
14. • Social networking: A social structure made
of nodes that are generally individuals or
organizations. A social network represents
relationships and flows between people,
groups, organizations, animals, computers or
other information/knowledge processing
entities. The term itself was coined in 1954 by
J. A. Barnes.
