Computer programming

Computer programming (often shortened to programming, scripting, or coding) is the process of designing, writing, testing, debugging, and maintaining the source code of computer programs. This source code is written in one or more programming languages (such as Java, C++, C#, Python, etc.). The purpose of programming is to create a set of instructions that computers use to perform specific operations or to exhibit desired behaviors. The process of writing source code often requires expertise in many different subjects, including knowledge of the application domain, specialized algorithms and formal logic.
Within software engineering, programming (the implementation) is regarded as one phase in a software development process.
There is an ongoing debate on the extent to which the writing of programs is an art form, a craft, or an engineering discipline.^[1] In general, good programming is considered to be the measured application of all three, with the goal of producing an efficient and evolvable software solution (the criteria for "efficient" and "evolvable" vary considerably). The discipline differs from many other technical professions in that programmers, in general, do not need to be licensed or pass any standardized (or governmentally regulated) certification tests in order to call themselves "programmers" or even "software engineers." Because the discipline covers many areas, which may or may not include critical applications, it is debatable whether licensing is required for the profession as a whole. In most cases, the discipline is self-governed by the entities which require the programming, and sometimes very strict environments are defined (e.g. United States Air Force use of AdaCore and security clearance). However, representing oneself as a "Professional Software Engineer" without a license from an accredited institution is illegal in many parts of the world.
Another ongoing debate is the extent to which the programming language used in writing computer programs affects the form that the final program takes. This debate is analogous to that surrounding the Sapir–Whorf hypothesis^[2] in linguistics and cognitive science, which postulates that a particular spoken language's nature influences the habitual thought of its speakers. Different language patterns yield different patterns of thought. This idea challenges the possibility of representing the world perfectly with language, because it acknowledges that the mechanisms of any language condition the thoughts of its speaker community.
source: http://en.wikipedia.org/wiki/Computer_programming

 

What is a Network?

What is a Network?

 

A network is basically a set of two or more articles that are linked so the computers can share resources, such as printers, software, and internet connections. Networked computers can also share files without having to transfer data using a disk or data key. And users of networked computers can also communicate electronically without use of the internet.
Computers within a network can be linked several ways: though cables, telephone lines, radio waves, satellites, or infrared beams. There are also three basic types of networks: Local Area Networks (LANs), Metropolitan Area Networks (MANs), and Wide Area Networks (WANs).
 

Local Area Networks

A Local Area Network (LAN) is basically a smaller network that's confined to a relatively small geographic area. LAN computers are rarely more than a mile apart. Examples of common LANs are networked computers within a writing lab, school, or building.
Within a LAN network, one computer is the file server. This means that it stores all software that controls the network, and it also stores the software that can be shared among computers in the network. The file server is the heart of the LAN.
The computers attached to the file server are called workstations. Workstations can be less powerful than the file server because they don't have to store as many files and applications as the file server, and they are not always on and working to keep the network up and running. However, workstations may also have additional software stored on their hard drives. Most LANS are connected using cables.
 

Metropolitan Area Networks

A Metropolitan Area Network (MAN) connect 2 or more LANs together but does not span outside the boundaries of a city, town, or metropolitan area. Within this type of network is also the Campus Area Network (CAN), which is generally smaller than a MAN, connecting LANs within a limited functional area, like a college campus, military base, or industrial complex.
 

Wide Area Networks

Wide Area Networks connect larger geographic areas. Often, smaller LANs are interconnected to form a large WAN. For instance, an office LAN in Los Angeles may be connected to office LANs for the same company in New York, Toronto, Paris, and London to form a WAN spanning the whole company. The individual offices are no longer part of individual LANs, they are instead part of a worldwide WAN.
The connection of this type of network is complicated. WANs are normally connected using multiplexers connect local and metropolitan networks to global communications networks like the Internet.
source: http://www.spamlaws.com/what-is-network.html

Communication media

Communication media

 

Computer networks can be classified according to the hardware and associated software technology that is used to interconnect the individual devices in the network, such as electrical cable (HomePNA, power line communication, G.hn), optical fiber, and radio waves (wireless LAN). In the OSI model, these are located at levels 1 and 2.
A well-known family of communication media is collectively known as Ethernet. It is defined by IEEE 802 and utilizes various standards and media that enable communication between devices. Wireless LAN technology is designed to connect devices without wiring. These devices use radio waves or infrared signals as a transmission medium.

Wired technologies

The order of the following wired technologies is, roughly, from slowest to fastest transmission speed.

• Twisted pair wire is the most widely used medium for telecommunication. Twisted-pair cabling consist of copper wires that are twisted into pairs. Ordinary telephone wires consist of two insulated copper wires twisted into pairs. Computer networking cabling (wired Ethernet as defined by IEEE 802.3) consists of 4 pairs of copper cabling that can be utilized for both voice and data transmission. The use of two wires twisted together helps to reduce crosstalk and electromagnetic induction. The transmission speed ranges from 2 million bits per second to 10 billion bits per second. Twisted pair cabling comes in two forms: unshielded twisted pair (UTP) and shielded twisted-pair (STP). Each form comes in several category ratings, designed for use in various scenarios.

• Coaxial cable is widely used for cable television systems, office buildings, and other work-sites for local area networks. The cables consist of copper or aluminum wire surrounded by an insulating layer (typically a flexible material with a high dielectric constant), which itself is surrounded by a conductive layer. The insulation helps minimize interference and distortion. Transmission speed ranges from 200 million bits per second to more than 500 million bits per second.

• ITU-T G.hn technology uses existing home wiring (coaxial cable, phone lines and power lines) to create a high-speed (up to 1 Gigabit/s) local area network.

• An optical fiber is a glass fiber. It uses pulses of light to transmit data. Some advantages of optical fibers over metal wires are less transmission loss, immunity from electromagnetic radiation, and very fast transmission speed, up to trillions of bits per second. One can use different colors of lights to increase the number of messages being sent over a fiber optic cable.

Wireless technologies

• Terrestrial microwave – Terrestrial microwave communication uses Earth-based transmitters and receivers resembling satellite dishes. Terrestrial microwaves are in the low-gigahertz range, which limits all communications to line-of-sight. Relay stations are spaced approximately 48 km (30 mi) apart.

• Communications satellites – The satellites communicate via microwave radio waves, which are not deflected by the Earth's atmosphere. The satellites are stationed in space, typically in geosynchronous orbit 35,400 km (22,000 mi) above the equator. These Earth-orbiting systems are capable of receiving and relaying voice, data, and TV signals.

• Cellular and PCS systems use several radio communications technologies. The systems divide the region covered into multiple geographic areas. Each area has a low-power transmitter or radio relay antenna device to relay calls from one area to the next area.

• Radio and spread spectrum technologies – Wireless local area network use a high-frequency radio technology similar to digital cellular and a low-frequency radio technology. Wireless LANs use spread spectrum technology to enable communication between multiple devices in a limited area. IEEE 802.11 defines a common flavor of open-standards wireless radio-wave technology.

• Infrared communication can transmit signals for small distances, typically no more than 10 meters. In most cases, line-of-sight propagation is used, which limits the physical positioning of communicating devices.

• A global area network (GAN) is a network used for supporting mobile across an arbitrary number of wireless LANs, satellite coverage areas, etc. The key challenge in mobile communications is handing off user communications from one local coverage area to the next. In IEEE Project 802, this involves a succession of terrestrial wireless LANs.^[4]

Exotic technologies

There have been various attempts at transporting data over exotic media:

• IP over Avian Carriers was a humorous April fool's Request for Comments, issued as RFC 1149. It was implemented in real life in 2001.^[5]

• Extending the Internet to interplanetary dimensions via radio waves.^[6]

Both cases have a large round-trip delay time, which prevents useful communication.
source :http://en.wikipedia.org/wiki/Computer_network

Computer network

A computer network, or simply a network, is a collection of computers and other hardware interconnected by communication channels that allow sharing of resources and information.^[1] Where at least one process in one device is able to send/receive data to/from at least one process residing in a remote device, then the two devices are said to be in a network. A network is a group of devices connected to each other. Networks may be classified into a wide variety of characteristics, such as the medium used to transport the data, communications protocol used, scale, topology, benefit, and organizational scope.
Communications protocols define the rules and data formats for exchanging information in a computer network, and provide the basis for network programming. Well-known communications protocols include two Ethernet, a hardware and link layer standard that is ubiquitous in local area networks, and the Internet protocol suite, which defines a set of protocols for internetworking, i.e. for data communication between multiple networks, as well as host-to-host data transfer, and application-specific data transmission formats.
Computer networking is sometimes considered a sub-discipline of electrical engineering, telecommunications, computer science, information technology or computer engineering, since it relies upon the theoretical and practical application of these disciplin

source: http://en.wikipedia.org/wiki/Computer_network

What are the components of a CPU?

 The CPU is comprised of three main parts:

ALU (Arithmetic Logic Unit): Does the actual logical comparisons that need to be processed.

Control Unit: Can execute or store the results coming out of the ALU.

Registers: Stores the data that is to be executed next.

How to use your computer

How to use your computer

The Mouse

The Mouse is the device you will use for most of your interactions with your PC. It is primarily used to move the pointer arrow around the screen and to select and activate options.
The mouse buttons are used to interact with whatever is on the screen where the pointer is located. The left mouse button is the one you will use most often. Clicking this tells the PC to select an item and is called 'left-clicking'. To activate an item and use it, you will often need to click the button twice or 'double-click'.
If you click and hold the left button and move the mouse, this has the effect of 'dragging' a selected object about the screen until you release the button.
Left-clicking on text in a document will place a flashing cursor at that point, which allows you to begin typing there.
The right mouse button is usually used to bring up a small menu window that gives options specific to the selected object. To use a particular option you just left-click it.
Common right-click menu options for an object include: Open (activate, same as if you double-click), Cut (remove to be placed elsewhere), Copy (make a copy of this object) , Create Shortcut (create a shortcut link elsewhere to give quick access to this object), Delete (remove permanently), Rename (give a new name), and Properties (find out information).
You may have a third smaller button in the center of your mouse that can be rolled forwards and backwards. This mouse-wheel can be used to move up and down through documents.

The Keyboard

Keyboards can come in a number of different layouts. QWERTY keyboards are so-called because the top line of letters, underneath the number line, begins with those six letters.
There are a number of other useful keys too. The Enter key confirms a selection, and pressing the Shift or Caps Lock keys activates uppercase letters when you type, or special characters on number keys.
There are a number of function keys beginning with F1, F2 and so on, and these are used to access different options in different programs. Other keys such as Home, End and Page Up and Page Down allow you to quickly move about within a document.
The arrow keys move the text typing cursor up, down, left or right.
You may have a number keypad too. This acts as an alternative to the number keys above the main letter keys. Pressing the Num Lock button will switch between using the keypad as number keys, or arrow keys.
There are certain key combinations that can be used to perform particular tasks. See Keyboard Shortcuts for more information.

The Desktop

The Desktop is the main background on your screen when you are working on your PC. It consists of a background picture or 'wallpaper', any program shortcuts you have created, and the Taskbar.
The Taskbar runs along the bottom of the screen (or the side, or top - you can click and drag it wherever you want to place it) and shows the date and time as well as giving you access to the Start menu. You can also put program shortcuts on the taskbar so that one click will activate a particular program.
Left-clicking on the Start menu brings up the All Programs list of shortcuts to programs you have on your computer. These are often arranged in 'folders', so that you can find all the programs made by one company under a folder in their name.
By holding the mouse pointer over a folder you will see a new list appear of whatever programs are within that folder. Some programs will have several related entries - so you might see a README (a document that has instructions for using the program), or an option to Uninstall (remove the program from your PC).
You can access your Desktop settings by right-clicking anywhere on the background wallpaper and then clicking on Properties.

Windows

The operating system that runs all your programs and allows you to easily interact with your PC is called Windows for a good reason. It allows you to work with several different items and programs at once, all in their own 'window'. A window is like a smaller screen contained within a box on your main screen.
When you are working with a window it is brought to the 'front' of the screen, overlapping the Desktop and any other items behind it, so that you can focus on whatever is in the window.

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In this way, you can have several windows open at the same time containing different programs that can be opened, closed, and re-arranged across the screen. This means you can do multiple tasks at the same time, such as playing your favorite music while writing an e-mail for example.

Files And Folders

Every item stored on your PC, whether it is a document, picture, song, game or whatever, is a file. A file can only be activated by programs that understand and are able to use it.
For example, you cannot use a music program to open a letter document. Each program on your computer understands what type of file it can or cannot use by the fact that every file has a filetype given to it.
This takes the form of a few extra letters or numbers added on to its name after a full stop. So for example, 'myletter.doc' is a file named 'myletter' with the filetype '.doc', meaning it will require a program that understands doc (document) files, such as Microsoft Word.
There are many different filetypes. Read Common Filetypes for a list of the more common.
Any one single program or application can actually consist of many different files, all working together to achieve the same task.
This means modern computers can have millions of files spread across different locations. Folders help organize these files, so that for each particular program there can be one folder that contains all the files it needs in one place.
A folder can even contain other folders inside it called 'sub-folders'. For example, to organize your holiday pictures together you might have a folder called 'Holidays 2006' and then other sub-folders within that for each particular holiday destination, for example 'France 2006'.
You can create your own folders. You can also create shortcuts to make it easier to find particular files. Read Organize Your Files/Folders/Shortcuts to learn more.
You can take a look at an example of a folder now. On your Desktop you should see a shortcut icon called My Documents. Double-clicking this will open a new window showing the contents of the My Documents folder.

My Documents

My Documents is a folder on your computer that is automatically created for you, so that you can store all your own files in one place away from all the program and system folders, making them easier to find.
Double-click the My Documents shortcut on the Desktop and you will see a list of folders, within which are your files. To see what is inside a folder, double-click on it and the current window will change to show the contents.
You may see some other folders which have been automatically created for you to help you store certain types of files, such as My Music, My Pictures and My Videos. However, you do not have to use these, and you can store any of your files in any folder you want to. You don't even have to use My Documents, though it is usually easier if you do.

My Computer

Close any open windows by clicking the X button in the top-right. On your Desktop, double-click the My Computer shortcut and you will see a list of locations where files are stored on your PC's disk drives.
If you double-click the Local Disk (your Hard Disk, usually C: ) you can see all the folders that are stored on your Hard Disk - this will be the part of your PC where all your files are usually kept, unless you have extra disk drives.
The Program Files and Windows folders here are especially important, and should usually not be changed as they contain the files necessary for programs and Windows to run.
All files take up 'disk space' and your computer only has so much room to store them all. If you want to see how much of your Hard Disk you have used up so far, and how much space you have left, double-click My Computer again and this time, instead of double-clicking the Local Disk, right-click it and select Properties.
If you find you are running out of disk space, you should try to clean up some unnecessary files. Read Clean Out And Clean Up Files for more information.
If you decide you need a lot more space than you have, it is possible to buy extra Hard Drives and connect them to your computer.
If you right-click the My Computer icon on the Desktop rather than double-clicking it, and then click on Properties, you can see detailed information about your PC including your hardware devices and performance settings.

The Control Panel

The Control Panel is a collection of all the important options you will need when you want to change settings on your computer. You can find control icons for display, sound, Internet, hardware, programs, security and system settings. To access the Control Panel, click the Start menu and then click Control Panel.
Changing settings in the Control Panel can make big changes to your PC's setup. For example, the Appearance and Themes or Display options in the Control Panel can affect the quality of your screen and the size of text. Read Change Display Settings And Text Size for more information.
Click on your Start menu and then Help and Support for more help with using your PC and particular Windows features.
source: http://www.easycomputertips.com/article-howtouseyourpc-thebasics.html

How to Create a Popular Website Like Facebook

 

Instructions

1. • 1
     Go to a free social networking host site such as Zonkk.com, Ipernity.com or Sixgroups.com and create a name for your site. In Zonkk.com, type it in the blank box under the "Name Your Social Network" button.
     
   • 2
     Create a web address for your social network using letters only (i.e. rememberme). Type your web address in the box under the "Pick a Web Address" button. After your web address, the extension, zonkk.com appears, meaning your social network is a subdomain. This represents the easiest and most economical way to start your network and test what features work best for your networkers.
     Click the "Create" button. This takes you to a free sign-up page to enter your personal information including your user name and e-mail. Read the terms and click on the "I Agree to the Terms" button.
     
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   • 3
     Add applications to customize your network. Allow users to comment or write blogs on your network. In Zonkk.com, click on "Applications" for a list of different applications. Click the "Enable" button alongside "Blogs." The message saying "Plugin blog has become enabled" means members on your network can add comments or blogs.
     
   • 4
     Click "Enable" on the "Applications" list alongside the video application. Next, click on "Video Settings" on the list of commands on the left side of the page. Under "Background Color for Player," enter the hex value of color. For example, for white, enter FFFFFF. Next, enter the foreground color, then click "Save Settings." This feature allows users to put up videos.
     
   • 5
     Click on "Applications" in the column on the left side of the page. Click on the "Enable" button alongside "Gifts." The message "Plugin gifts has become enabled" allows users to exchange virtual gifts. Continue customizing your site with other listed applications you want to add.
     
   • 6
     Bring in networkers. Invite friends from other sites. If you design your site specifically around a hobby or sport, find other sport or hobby forums and invite other enthusiasts. Build your site day by day by visiting other popular social sites and introducing your own.
     
   • 7
     Branch out to your own domain. After building a successful network of followers, Tharon Howard, author of "Design to Thrive," recommends taking the same interface you created with your subdomain and creating your own domain and linking it to your subdomain to make the transition seamless.
     source: http://www.ehow.com/how_6860115_create-popular-website-like-facebook.html