Software

The software is the information that the computer uses to get the job done. Software needs to be accessed before it can be used. There are many terms used for the process of accessing software including running, executing, starting up, opening, and others.
Computer programs allow users to complete tasks. A program can also be referred to as an application and the two words are used interchangeably.
Examples of software programs or applications would be the Operating System (DOS, Windows, UNIX, MacOS and various others), Wordprocessor (typing letters), Spreadsheet (financial info), Database (inventory control and address book), Graphics program, Internet Browser, Email and many others.
As well any document that you create, graphic you design, sound you compose, file you make, letter you write, email you send or anything that you create on your computer is referred to as software. All software is stored in files.
Software is stored on a disk, card, tape or one of the dozens of other storage devices available.
There are millions of different pieces of software available for almost every conceivable need. Software is available commercially through stores and mail order and also available on the Internet. Software is also available through an Open Source license which allows anyone to use the Open Source software free of charge as long as the license is maintained. If you can't find the application that you need software development companies can custom designed software for you.
The largest software companies offer packages of software or suites that include many of the programs that the average person or business needs. Software packages or suites contain programs that work together and share information, making it easier to combine that information in versatile ways. For example when writing a letter you can get the mailing address from an address book, include a letterhead from a graphics program and include a financial chart from a spreadsheet and combine this collection of information in the body of the letter.
The three basic types of software are; commercial, shareware and open source software. Some software is also released into the public domain without a license.

Commercial software comes prepackaged and is available from software stores and through the Internet.
Shareware is software developed by individual and small companies that cannot afford to market their software world wide or by a company that wants to release a demonstration version of their commercial product. You will have an evaluation period in which you can decide whether to purchase the product or not. Shareware software often is disabled in some way and has a notice attached to explain the legal requirements for using the product.
Open Source software is created by generous programmers and released into the public domain for public use. There is usually a copyright notice that must remain with the software product. Open Source software is not public domain in that the company or individual that develops the software retains ownership of the program but the software can be used freely. Many popular Open Source applications are being developed and upgraded regularly by individuals and companies that believe in the Open Source concept.

Operating Systems

All computers need some sort of Operating System (OS). The majority of modern home computers use some form of Microsoft's operating systems. The original Microsoft operating system was called DOS (Disk Operating System) though most computers use Windows. Windows comes in various versions beginning with version 3.x then 95, 98, ME, XP, Vista and currently version 7. A few computers use IBM's O/S2. Apple's Mac use their own operating system beginning with OS 1 though to OS 10.x. In the past large companies and institutions would have an operating system design exclusively for them but as the commercial operating systems become more sophisticated the benefits of this practice is becoming less apparent. Some computer professionals, Internet Service Providers (ISP) and mainframe computer users use an operating system such as UNIX (or a variant such as Linux), Windows NT or 2000 (Win2k) or one of the other network or server based operating systems.
There are many smaller operating systems out there. The problem is that software is currently being developed only for the main operating systems and only the newest versions of these OS. Many older computers with unique operating systems have lots of software already developed for them but there is very little new software being developed for the older computers. The older operating systems are less likely to offer technical support than the more modern operating systems.
The operating system controls the input and output or directs the flow of information to and from the CPU. Much of this is done automatically by the system but it is possible to modify and control your system if you need to.
When you turn your computer on it first needs to load the operating system sometimes referred to a booting up. Basically the computer starts from scratch every time you turn the power on.
It checks all its components and will usually display a message if there is a problem. Loading the system is usually automatic.
Once the system is loaded the user can start the application or program that they are going to use.
Most computer users will run Microsoft Windows, Mac OS or Linux as their operating system. These OS are Graphic User Interface (GUI) which allows the user to control or run the computer using a Mouse and Icons. The user simply moves the mouse on a flat surface, rolls the trackball, or moves their hand over the touchpad to control a pointer. They then choose the option they want by pressing a button or touching the pad.
Without a GUI the user controls the computer using the keys on the keyboard. This is referred to as a Command Line Interface (CLI)

Disk and Storage

Disks and cards are used to store information. All information on computers is stored in files. The size of a file is measured in bytes.
A byte is approximately one character (letter 'a', number '1', symbol '?' etc....).
A byte is made up of 8 bits. A bit is simply an on or an off signal which passes through the computers circuitry. Every piece of software can be broken down into a series of on or off signals or it's Binary Code.

• About a thousand bytes is a kilobyte (Kb).
• About a million bytes is a megabyte (Mb).
• About a billion bytes is a gigabyte (Gb).
• About a trillion bytes is a terabyte (Tb)

* Editor's Note: I say 'about' because everything in computers must be divisible by 8 so a kilobyte is actually 1,024 bytes. The reason for this goes beyond the scope of an introductory level document but as it can cause some confusion I thought it should be mentioned.

Disk are a common way of transporting information such as bringing files home from work or sharing files. Floppy disks have become less useful as file sizes increase and Compact disks (CDs), Flash drives and Digital Video Devices (DVDs) are becoming more popular. Most software is sold on a CD. Internal Hard disks are the most common storage device.
Compact disks or CDs can store large amounts of information. One disk will store 650 Mb. One type is a CD-ROM which stand for Compact Disk Read Only Memory. Another type is a CD-RW which stands for Compact Disk - Read/Write. CD drives can copy information or burn information on to a blank CD. Common Read Only CD blanks can only be written to once though more expensive Read/Write CD's can be used over and over again.
DVD disks can store 4.5 Gb on standard disk, 8 Gb on a dual layer disk and 16 Gb on a blue-ray disk.
Digital recorders allow you to store large files, such as movies, on a single disk.
Hard disks store the majority of information on today's modern computer. Some of the first hard disk stored 10 to 40 Mb. Today the standard hard disk stores 150 Gb or more (this number is constantly increasing). Information can be stored and deleted as necessary. As files get larger the speed that hard disks can read and write become more important.
Flash drive or thumb drives range in size.
Floppy disk or diskette comes in two basic sizes; 5.25 inch and 3.5 inch. Both have a low and high density versions though 3.5 inch high density disks are the most common though many modern computers are being sold without floppy disk drives.

Disk size	Amount of storage	Approximate printed 8.5 x 11 inch pages
3.5 high density	1.44 Mb	720 pages
CD	650 Mb	a small library
DVD	4.5 Gb	a feature length movie
DVD dual layer	8 Gb	a long feature length movie with extras

There are many other storage devices including tapes, Panasonic's LS120 3.5 inch diskettes, Iomega's Zip & Jazz disks, VCR tape and many others. Innovation in storage technology is advancing rapidly and some technologies become obsolete..
Information is stored in an electromagnetic form much like a cassette or video tape.

Note: Keep disks away from strong electric or magnetic fields including x-rays. Be aware of high electromagnetic areas in the room such as televisions, speakers, high tension wires, etc... Use disks only at room temperature and keep them out of direct sunlight. If possible avoid passing electromagnetic storage devices through airport x-rays. In theory information stored on a disk will last indefinitely but the physical storage device will wear out with usage and time so be sure to back up (copy) your important files to a second storage device.