Friday, 8 January 2016

CONNECTING TO THE INTERNET

MODEM-A modem (modulator-demodulator) is a network hardware device that modulatesone or more carrier wave signals to encode digital information for transmission anddemodulates signals to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data. Modems can be used with any means of transmitting analog signals, from light emitting diodes to radio. A common type of modem is one that turns the digital dataof a computer into modulated electrical signal for transmission over telephone linesand demodulated by another modem at the receiver side to recover the digital data.
Modems are generally classified by the amount of data they can send in a given unit of time, usually expressed in bits per second (symbol bit/s, sometimes abbreviated "bps"), or bytes per second (symbol B/s). Modems can also be classified by their symbol rate, measured in baud. The baud unit denotes symbols per second, or the number of times per second the modem sends a new signal. For example, the ITU V.21 standard used audio frequency shift keying with two possible frequencies, corresponding to two distinct symbols (or one bit per symbol), to carry 300 bits per second using 300 baud. By contrast, the original ITU V.22 standard, which could transmit and receive four distinct symbols (two bits per symbol), transmitted 1,200 bits by sending 600 symbols per second (600 baud) using phase shift keying.


BROADBAND- is a wide bandwidth data transmission with an ability to simultaneously transport multiple signals and traffic types. The medium can be coaxial cable, optical fiber, radio or twisted pair.




CABLE MODEM- A cable modem is a device that enables you to hook up your PC to a local cable TV line and receive data at about 1.5 Mbps. This data rate far exceeds that of the prevalent 28.8 and 56 Kbps telephone modems and the up to 128 Kbps of Integrated Services Digital Network (ISDN) and is about the data rate available to subscribers of Digital Subscriber Line (DSL) telephone service. A cable modem can be added to or integrated with a set-top box that provides your TV set with channels for Internet access. In most cases, cable modems are furnished as part of the cable access service and are not purchased directly and installed by the subscriber.



DSL-  (Digital Subscriber Line) is a technology for bringing high- bandwidth information to homes and small businesses over ordinary copper telephone lines. xDSL refers to different variations of DSL, such as ADSL, HDSL, and RADSL.





SATTELITE BROADBAND-  is Internet access provided through communications satellites. Modern satellite Internet service is typically provided to users through geostationary satellites that can offer high data speeds,[2] with newer satellites using Ka band to achieve downstream data speeds up to 50 Mbps.


WIRELESS-Wireless networking is a method by which homes, telecommunications networks and enterprise (business) installations avoid the costly process of introducing cables into a building, or as a connection between various equipment locations. Wireless telecommunications networks are generally implemented and administered using radio communication. This implementation takes place at the physical level (layer) of the OSI model network structure.





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Friday, 27 November 2015

INTERNET TERMS AND DEFINITION

ANTI-VIRUS PROGRAM- An antivirus program is a software utility designed to protect your computer or network against computer viruses.

Glossary of Antivirus Terms

Adware
Software that displays advertising banners on Web browsers. While not always threatening, these programs create pop-ups and can cause sluggishness in network connectivity.
Grayware
Programs that are undesirable but less serious or troublesome as malware.  Grayware includes some spyware, adware, and joke programs.
Malware
From Malicious Software; malware refers to software that is meant to infiltrate or damage a computer system without the owner's consent and, in many cases, knowledge. Malware programs include computer viruses, rootkits, spyware, and trojan horses.
Rootkit
A malware program that is designed to take full control of the machine's operating system.
Safe Mode
A diagnostic mode used by a computer operating system.  In safe mode, an operating system will have reduced functionality, but isolating problems is much easier. For details, see Restarting Your Computer in Safe Mode.
Spyware
Computer software that is installed (unknowingly) on a personal computer that is meant to intercept information and/or take partial control over a user's interaction with the machine. Most spyware programs record various personal information, such as surfing habits, and actively redirect Web Browsers or install 3rd party software without permission.
Trojan Horse
A program that appears as a legitimate and desirable program, but in actuality, performs undisclosed malicious functions on the machine. Most computer worms are trojan horses to hide the fact that access has been opened to intruders.
Virus
A malware computer program that can copy itself and infect a computer without permission or knowledge of the user. Some viruses damage computers by damaging files.  Others open connections for people to take over the machine.
Worm
A self-replicating program that uses a network to send copies of itself to other machines, often without any user intervention. At times, the only harm a worm causes is lowered bandwith as it spreads on the network.  However, one of the most common uses of a worm is to install a backdoor on a computer for someone to gain access.
APPLET- An applet is a little application. Prior to the World Wide Web, the built-in writing and drawing programs that came with Windows were sometimes called "applets." On the Web, using Java, the object-oriented programming language, an applet is a small program that can be sent along with a Web page to a user. Java applets can perform interactive animations, immediate calculations, or other simple tasks without having to send a user request back to the server.

Related Terms


ARCHIVE-  is an accumulation of historical records or the physical place they are located.[1] Archives contain primary source documents that have accumulated over the course of an individual or organization's lifetime, and are kept to show the function of that person or organization. Professional archivists and historians generally understand archives to be records that have been naturally and necessarily generated as a product of regular legal, commercial, administrative or social activities. They have been metaphorically defined as "the secretions of an organism",[2] and are distinguished from documents that have been consciously written or created to communicate a particular message to posterity.

Related Terms


 ASCII-  stands for American Standard Code for Information Interchange. Computers can only understand numbers, so an ASCII code is the numerical representation of a character such as 'a' or '@' or an action of some sort.

Related Terms


 BANDWIDTH- is in contrast to the field of signal processing, wireless communications, modem data transmission, digital communications, and electronics, in which bandwidth is used to refer to analog signal bandwidth measured in hertz, meaning the frequency range between lowest and highest attainable frequency while meeting a well-defined impairment level in signal power.

Related Terms


 BAND RATE- 

 BSS- A bulletin board system, or BBS, is a computer server running custom software that allows users to connect to the system using a terminal program. Once logged in, the user can perform functions such as uploading and downloadingsoftware and data, reading news and bulletins, and exchanging messages with other users through email, public message boards, and sometimes via direct chatting. Many BBSes also offer on-line games, in which users can compete with each other, and BBSes with multiple phone lines often provide chat rooms, allowing users to interact with each other. Bulletin board systems were in many ways a precursor to the modern form of the World Wide Web, social networks and other aspects of the Internet. Low-cost, high-performance modems drove online use through the early 1990s, both online services and BBSes. Infoworld estimated there were 60,000 BBS systems serving 17 million users in the US alone in 1994, a collective market much larger than the major online services like CompuServe.
The introduction of inexpensive dial-up internet service and the Mosaic web browser offered ease-of use and global access that BBS and online systems did not provide, and led to a rapid crash in the market starting in 1994. Over the next year, many of the leading BBS software providers went bankrupt and tens of thousands of BBSes disappeared. Today, BBSing survives largely as a nostalgic hobby in most parts of the world, but it is still an extremely popular form of communication for Taiwanese youth (see PTT Bulletin Board System) and in China.[1] Most BBSes are now accessible over Telnet and typically offer free email accounts, FTP services, IRC and all of the protocols commonly used on the Internet. Some offer access through packet switched networks, or packet radio connections.

Related Terms

BINARY- Pertaining to a number system that has just two unique digits. For most purposes, we use the decimal number system, which has ten unique digits, 0 through 9. All other numbers are then formed by combining these ten digits. Computers are based on the binary numbering system, which consists of just two unique numbers, 0 and 1. All operations that are possible in the decimal system (addition, subtraction, multiplication, division) are equally possible in the binary system.
We use the decimal system in everyday life because it seems more natural (we have ten fingers and ten toes). For the computer, the binary system is more natural because of its electrical nature (charged versus uncharged).
In the decimal system, each digit position represents a value of 10 to the position's power. For example, the number 345 means:

Related Terms

BITMAP- The standard bit-mapped graphics format used in the Windowsenvironment. By convention, graphics files in the BMP format end with a.BMP extension.
BMP files store graphics in a format called device-independent bitmap (DIB).

Related Terms

BLOG OR BLOGGING- 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.

Related Terms

BOOKMARK- To mark a document or a specific place in a document for later retrieval. Nearly all Web browsers support a bookmarking feature that lets you save the address (URL) of a Web page so that you can easily re-visit the page at a later time.
(n) A marker or address that identifies a document or a specific place in a document.

Related Terms

BOUNCE-  is used to describe an e-mail that has bounced back to the sender undelivered after it has already been accepted by the recipient's mail server.
Compare with hard bounce.

Related Terms

BUG- An error or defect in software or hardware that causes a program to malfunction. Often a bug is caused by conflicts in software when applications try to run in tandem. According to folklore, the first computer bug was an actual bug. Discovered in 1945 at Harvard, a moth trapped between two electrical relays of the Mark II Aiken Relay Calculator caused the whole machine to shut down.

Related Terms

BYTE- Abbreviation for binary term, a unit of storage capable of holding a single character. On almost all modern computers, a byte is equal to 8 bits. Large amounts of memory are indicated in terms ofkilobytes (1,024 bytes), megabytes (1,048,576 bytes), andgigabytes (1,073,741,824 bytes).

Related Terms

CGI- A CGI form is a way for an Internet user to interact dynamically with a Web server. An HTML page that contains a form may use a CGI program to process the form's data once it has been submitted. For example: a user visits a Web page looking for specific information on a topic and finds that the Web page offers an e-mail newsletter service. In order for the user to receive the newsletter, he must fill out a CGI form with all of his applicable information. The form is then sent to the server using CGI, and the server processes the information that was sent in the form in order to add the user to its database and initiate the user's newsletter service.
CHAIN LETTER-

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