Modem
Short for modulator-demodulator. A modem is a device or program that enables a computer to transmit data over, for example, telephone or cable lines. Computer information is stored digitally, whereas information transmitted over telephone lines is transmitted in the form of analog waves. A modem convertsbetween these two forms.
Network Card
A network interface controller (NIC) (also known as a network interface card, network adapter, LAN adapter and by similar terms) is a computer hardware component that connects a computer to a computer network.[1]
Early network interface controllers were commonly implemented on expansion cards that plugged into a computer bus; the low cost and ubiquity of the Ethernet standard means that most newer computers have a network interface built into the motherboard.
Wireless Network Card
A wireless network interface controller (WNIC) is a network interface controller which connects to a radio-based computer network rather than a wire-based network such as Token Ring or Ethernet. A WNIC, just like other NICs, works on the Layer 1 and Layer 2 of the OSI Model. A WNIC is an essential component for wireless desktop computer. This card uses an antenna to communicate through microwaves. A WNIC in a desktop computer usually is connected using the PCI bus. Other connectivity options are USB and PC card. Integrated WNICs are also available, (typically in Mini PCI/PCI Express Mini Card form).
The term is usually applied to IEEE 802.11 adapters; it may also apply to a NIC using protocols other than 802.11, such as one implementing Bluetooth connections.
Network Switch
A network switch is a small hardware device that joins multiple computers together within one local area network (LAN). Technically, network switches operate at layer two (Data Link Layer) of the OSI model.
Network switches appear nearly identical to network hubs,
but a switch generally contains more intelligence (and a slightly
higher price tag) than a hub. Unlike hubs, network switches are capable
of inspecting data packets
as they are received, determining the source and destination device of
each packet, and forwarding them appropriately. By delivering messages
only to the connected device intended, a network switch conserves network bandwidth and offers generally better performance than a hub.
Yahoo! Inc. (Software Category)
Yahoo! Inc. is an American multinational internet corporation headquartered in Sunnyvale, California. It is widely known for its web portal, search engine Yahoo! Search, and related services, including Yahoo! Directory, Yahoo! Mail, Yahoo! News, Yahoo! Finance, Yahoo! Groups, Yahoo! Answers, advertising, online mapping, video sharing, fantasy sports and its social media website. It is one of the most popular sites in the United States.[3] According to news sources, roughly 700 million people visit Yahoo! websites every month.[4][5] Yahoo! itself claims it attracts "more than half a billion consumers every month in more than 30 languages."[6]
Google Inc.
Google Inc. is an American multinational corporation specializing in Internet-related services and products. These include search, cloud computing, software and online advertising technologies.[6] Most of its profits derive from AdWords.[7][8]
Google was founded by Larry Page and Sergey Brin while they were Ph.D. students at Stanford University.
Together they own about 16 percent of its shares. They incorporated
Google as a privately held company on September 4, 1998. An initial public offering followed on August 19, 2004. Its mission statement from the outset was "to organize the world's information and make it universally accessible and useful",[9] and its unofficial slogan was "Don't be evil".[10][11] In 2006 Google moved to headquarters in Mountain View, California.
The corporation has been estimated to run more than one million servers in data centers around the world[15] and to process over one billion search requests[16] and about twenty-four petabytes of user-generated data each day.[17][18][19][20] In December 2012 Alexa
listed google.com as the most visited website in the world. Numerous
Google sites in other languages figure in the top one hundred, as do
several other Google-owned sites such as YouTube and Blogger.[21] Its market dominance has led to criticism over issues including copyright, censorship, and privacy.[22][23]
Yahoo! Messenger
Yahoo! Messenger (sometimes abbreviated Y!M or YM) is an advertisement-supported instant messaging client and associated protocol provided by Yahoo!.
Yahoo! Messenger is provided free of charge and can be downloaded and
used with a generic "Yahoo! ID" which also allows access to other Yahoo!
services, such as Yahoo! Mail,
where users can be automatically notified when they receive new email.
Yahoo! also offers PC-PC, PC-Phone and Phone-to-PC service, file
transfers, webcam hosting, text messaging service, and chat rooms in
various categories.
Yahoo! Messenger was originally launched under the name Yahoo! Pager on March 9, 1998.[1]
In addition to instant messaging features similar to those offered by ICQ, it also offers (on Microsoft Windows)
features such as: IMVironments (customizing the look of Instant Message
windows, some of which include authorized themes of famous cartoons
such as Garfield or Dilbert), address-book integration and Custom Status Messages.[2] It was also the first major IM client to feature BUZZing and music-status. Another recently added feature is customized avatars. Yahoo! Messenger also allows users to access Yahoo! Chat Rooms.
As of December 14, 2012, all public chat rooms on Yahoo! Messenger
have been shut down as part of a series of features being
changed/added/deleted.[3][4]
Skype
Line
Kakao Talk
We Chat
ect..
Monday 10 June 2013
Sunday 9 June 2013
ICT : Notes for Computer Network
INTRODUCTION
In order for a network to properly operate, two categories of network communications components are needed; ‘Hardware’ and ‘Software’.
Computers, hub, switch, router, network interface cards and both wired and wireless communications
media fall under the ‘Hardware’category.
Operating systems and applications fall under the ‘Software’ category.
NETWORK COMMUNICATION CHANNELS
Signals which carry information in a communications system travel through a physical medium.
This physical medium is called a communications channel, or at other times a communications link, a communications line, or a communications medium.
Some common types of network communications channels are the:
1. twisted-pair wire
2. coaxial cable
3. fiber-optic cable
4. satelite systems
5. wireless systems (namely using radiowaves, microwaves and
infrared)
Communications channels provide the most basic level of connectivity medium for a network.
NETWORK INTERFACE CARDS AND NETWORKING DEVICES
The Network Interface Card or NIC is one of the most important communications devices for a PC.
The NIC provides connection between the computer and the network’s communications media.
This connection is necessary because the NIC functions as a data conversion device to move data from the PC’s system to the network medium and vice versa.
The Network Interface Card also supplies the basic addressing system used to get data from PC to PC across a network.
The other hardware component that is required for communications to work on a network is the networking device, such as the hub, switch, router and even the modem.
The function of these devices is generally to control the flow of data on a network.
In order for a network to properly operate, two categories of network communications components are needed; ‘Hardware’ and ‘Software’.
Computers, hub, switch, router, network interface cards and both wired and wireless communications
media fall under the ‘Hardware’category.
Operating systems and applications fall under the ‘Software’ category.
NETWORK COMMUNICATION CHANNELS
Signals which carry information in a communications system travel through a physical medium.
This physical medium is called a communications channel, or at other times a communications link, a communications line, or a communications medium.
Some common types of network communications channels are the:
1. twisted-pair wire
2. coaxial cable
3. fiber-optic cable
4. satelite systems
5. wireless systems (namely using radiowaves, microwaves and
infrared)
Communications channels provide the most basic level of connectivity medium for a network.
NETWORK INTERFACE CARDS AND NETWORKING DEVICES
The Network Interface Card or NIC is one of the most important communications devices for a PC.
The NIC provides connection between the computer and the network’s communications media.
This connection is necessary because the NIC functions as a data conversion device to move data from the PC’s system to the network medium and vice versa.
The Network Interface Card also supplies the basic addressing system used to get data from PC to PC across a network.
The other hardware component that is required for communications to work on a network is the networking device, such as the hub, switch, router and even the modem.
The function of these devices is generally to control the flow of data on a network.
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