A computer is an electronic device that manipulates information or "data." It has the ability to store, retrieve, and process data. You can use a computer to type documents, send email, and surf the Internet. You can also use it to handle spreadsheets, accounting, database management, presentations, games, and more.

Whether you realize it or not, computers play an important role in our lives. When you withdraw cash from an ATM, scan groceries at the store, or use a calculator, you're using a type of computer


Computers Simplified

Inside a Computer -- Part of the Computer Motherboard Inside a Computer -- Part of the Computer Motherboard For beginning computer users, the computer aisles at an electronics store can be quite a mystery, not to mention overwhelming. However, computers really aren't that mysterious. All types of computers consist of two basic parts – hardware and software.

Hardware is any part of your computer that has a physical structure, such as the computer monitor or keyboard. If you can touch it, it is hardware. Software is any set of instructions that tells the hardware what to do. It is what guides the hardware and tells it how to accomplish each task.

Anything you buy for your computer can be classified as either hardware or software. Once you learn more about these items, computers are actually very straightforward.

The first electronic computer, the Electronic Numerical Integrator and Computer (ENIAC), was developed in 1946. It measured 18 feet by 80 feet and weighed 30 tons.


What are the Different Types of Computers?

There are many types of computers, but personal computers such as desktop and laptop computers are probably the two type of computers that you think of first.

Desktop Computers

Example Desktop Computer Example Desktop Computer

Many people use desktop computers, or desktops as they are often referred to, at work, home, school, or the library. They can be small, medium, or large in style, and usually sit on a desk. The term desktop actually refers to the casing, or the tower. Once you add a monitor, mouse, and a keyboard, you have what is typically known as a desktop computer.

Most desktop computers are easy to upgrade and expand, or add new parts. In addition to expandability, another benefit of desktop computers is the cost. If you compare a desktop computer with 128 MB of RAM and a 2 GB hard drive to a laptop with the same features, you will most likely find that the desktop computer is priced lower.

The term desktop computer originated when the computer case was wide and flat, and was designed specifically to fit on your desktop with the monitor on top.

Laptop Computers
Example Laptop Computer Example Laptop Computer

The second type of computer that you may be familiar with is a laptop computer, or laptops as they are often referred to. Laptops are battery or AC-powered personal computers that can be easily carried and used in a variety of locations.

A quick glance at the size of a laptop and you might guess that it would be difficult to expand or upgrade. While the desktop computer case is relatively easy to open and access internal components, the small laptop case makes this more difficult in comparison; however, the primary benefit of a laptop computer is its small size and easy portability.

A laptop computer is sometimes called a notebook computer because of its size.


Types of Personal Computers

iMac all-in-one computer iMac all-in-one computer Two popular types of personal computers are the IBM compatible and Macintosh computers. The first personal computer was produced by IBM in 1981 and was called the IBM PC. In 1984, Apple Computer introduced the Macintosh, or Mac, and it became the first widely sold personal computer with a graphical user interface or GUI (pronounced gooey). Although both IBM and Apple computers are personal computers, the term PC came to refer to IBM or IBM-compatible personal computers.

Apple now produces a Macintosh computer called the iMac, which is a desktop computer that features an all-in-one design. This means all the internal components are located behind the monitor, rather than in a tower case, which is customary in desktop computers.

While our training is intended for people who use PCs and the Windows operating system, some of our information also applies to Macintosh computers.

Other Types of Computers

You may hear someone refer to a computer as a workstation or a server, especially at work. You may wonder how these two items are different from desktop computers.

Workstations are similar to desktop computers, but are more powerful and are usually connected to a network. Servers are specialized computers that store and deliver, or “serve up,” information to other computers on a network.

There are many different types of servers such as file servers, database servers, and web servers. For example, employees at a company might store all the business documents on a file server so that they can share files and access then from any computer on the network. When you use your browser to click a link, a web server delivers the page you requested on the Internet, the biggest network in the world.
What is an Operating System?

An operating system is the most important software that runs on a computer. You might be thinking, “OK, but what is software?” Software is any set of instructions that performs some task on a computer. The operating system performs many essential tasks for your computer.

It controls the memory needed for computer processes, manages disk space, controls peripheral devices, and allows you to communicate with the computer without knowing exactly how a computer works. Without an operating system, a computer is useless.


The Operating System's Job

Windows Operating System Loading Windows Operating System Loading You've probably heard the phrase boot your computer, but do you know what that means? Booting is the process that occurs when you press the power button to turn your computer on. At the end of at process, the operating system loads.

From this point, the operating system begins to do its job of controlling the way in which the computer functions. The operating system is responsible for managing the computer's hardware and software resources.

Basically, the operating system serves as the boss, or manager, and makes sure all the various parts of the computer get what they need.


Mac OS Loading Mac OS Loading When you use your personal computer, you may work on a Word document, print an email, and have your Internet browser open for web surfing, all at the same time. These three programs need attention from the central processing unit (CPU) to do whatever task that you, the user, are telling it to do.

These programs need memory and storage, and need to be able to send messages to devices such as the mouse and the printer to accomplish these tasks.

The operating system is responsible for handling these areas, as well as processor and network management.

What Makes This Job So Difficult?

Let's say you went to your local electronics store and bought language software to learn Spanish. How did the computer programmer who developed the software know that it would work on your computer?

The operating system provides a consistent way for software applications to work on various computers without needing to know specific details about each computer's hardware. It doesn't matter that each computer may have a different amount of memory or processor speed.


Types of Operating Systems

Microsoft Windows, Mac OS X, and Linux Logos Microsoft Windows, Mac OS X, and Linux Logos Operating systems usually come preloaded on the desktop and laptop computers that you can buy today. Most people use the operating system that comes with their computer, but it is possible to upgrade or even change operating systems.

The three most common operating systems for personal computers are Microsoft Windows, Apple Mac OS X, and Linux.


Start Menu on Windows GUI Start Menu on Windows GUI Each of these operating systems uses a graphical user interface (GUI), which allows the user to interact with the computer. Instead typing a command that tell the computer what to do, you can use graphical icons and text on the GUI to instruct the computer to perform a task.

For example, if you want your computer to open the browser, Internet Explorer, simply double-click the Internet Explorer icon on the desktop, or select it from the Start menu.

Many users associate the operating system with the GUI because this is the part of the operating system that the user interacts with on a daily basis.

Let's take a look at the graphical user interfaces of three popular operating systems.


Microsoft Windows

Microsoft created the operating system, Windows, in the mid-1980s. They have a version of the operating system that is designed for the home user, and a professional version, which is intended for businesses. The versions differ in the depth of networking, security, and multimedia support.

Windows is a proprietary software, which means that Microsoft has placed restrictions on how people can use or copy the software. Windows comes preloaded on most of the PCs sold today, and can also be purchased separately Various versions of the software are priced from $79 to $399 for home users.
Windows Vista Desktop Windows Vista Desktop

Microsoft has a big share of the operating system market. According to web analyst Net Solutions, over 90% of computer users have one of the Windows operating systems, such as Windows 98, Windows 2000, Windows XP, or the most recent Windows Vista, as of March 2008.

Windows Vista and Windows XP are often referred to as Vista and XP, respectively.

Visit the Windows section of the Microsoft website to learn more about this operating system.

Apple Mac OS

Mac OS is a line of operating systems created by Apple Inc. The Mac operating system is proprietary software that comes preloaded on all new Macintosh computers, or Macs. The most recent version of the operating system is called Mac OS X (pronounced Mac O-S Ten). Like Microsoft, Apple offers a professional version of the operating system that is intended for use on servers and a version of the operating system that is developed for home users.

Mac OS X Desktop Mac OS X Desktop

According to web analyst Net Solutions, Mac OS users account for almost 7.5% percent of the operating systems market as of March 2008. Although the percentage of users is low, especially in comparison to Windows users, Mac operating systems have seen a dramatic jump in growth in 2007. Mac computers are sleek and modern looking, which has started to appeal to many home users.

Two of the common version names of Mac OS X are Leopard and Tiger.

Linux

Linux is an open source, or free, operating system. Unlike Windows and Mac OS, Linux is not proprietary software and all the computer code that is part of the operating system can be used and modified by any user. Linux was started in the 1990s when Linus Torvalds, a person interested in creating a free operating system, developed the Linux (pronounce lynn-ux) kernal, which is computer code that is a central part of an operating system.

As an open source software, any individual or company can take the Linux kernal and modify and add to it. Hundreds of companies and individuals have taken the Linux kernal and added additional computer programs to create various versions of the Linux operating system. These versions are known as distributions and are available to download for free.

Ubuntu Desktop: A Version of Linux Ubuntu Desktop: A Version of Linux

Linux is extremely popular in businesses, especially for servers, because it is adaptable. According to Net Application statistics, Linux represents under 1% of the market share for home users, but it does offer an alternative to commercial operating systems.

Despite being used in many businesses for servers, you do not have need to have special programming skills to download and use Linux. In fact, if you want to try Linux, you don't have to actually install it on your computer. Several versions of the operating system can be downloaded and burned to a CD.

Two popular distributions of the software are Ubuntu and Red Hat. Ubuntu is completely free and is available in a version geared specifically for home users. Red Hat is a company that offers technical and training support for businesses that use its version of the operating system, Red Hat Linux.