Introduction

This course is an introduction to computers, so maybe the first question to ask is,
What is a computer?

When I was a young child, computers were often seen as technological marvels and somewhat mysterious, since most people had never seen or used one. You probably think of a computer as the PC (Personal Computer) that you are using to take this course. It may not seem too mysterious, since you've grown up with devices like it in your home, but there was a time, not many years ago, when the idea of having a computer in the home would have seemed like science fiction.

Even more common-place than PCs are the many computers that are embedded in other devices.
Although you may not notice them very often, you are probably surrounded by computers without realizing it. For example, unless your family car is very old, it likely has several, maybe dozens, of small computers within it, each of which is performing some function that adds to the vehicle's capabilities. Video games, cell phones, digital cameras, even appliances, all have computers embedded within them.

How can we call all these devices, used in so many different places, by the name "computer"?
What are the common characteristics that each one has that allows us to group them together?

One way to answer that question is to say,
"A computer is a device, made up of hardware and software, that can perform certain tasks."

You may already have an idea what those words mean, but let's define them anyway.

Hardware is the actual electronics that make up the computer. It is the part that you can see and touch.

Software is the instructions and data that tell the computer what to do.

By the way, we will be defining a number of words during this course.
You can look up a word at any time by selecting "Tools" and then "Vocabulary".

Sometimes the instructions and data that perform a specific job is called a program.
For example, we might talk about a word processor program.
Now you might think that the software is the CD that you get when you buy a software package, but it isn't. The CD is just a way of storing the software (instructions and data).

So, we could say that a computer is some hardware (electronics) that runs software (performs instructions on data) to accomplish some task. For example,

Your PC hardware is running this course software to teach you about computing.

The computer hardware at a bank runs financial software that lets people write checks
or get cash from an ATM.

The microcircuit in your car's engine has instructions that process data to tell the engine how fast to run.

These are very different applications, but in each case we can correctly call the device a computer.

There are other ways we could answer the question of "What is a computer?" For example, some of the earliest computers were a type known as the analog computer, which works with numbers that vary continuously.

The computer type we will focus on in this course is the digital computer, which is a computer that works with numbers that vary in discrete steps. Your PC is a digital computer and we will explain more about that in a later lesson.

For now, I want to introduce one more concept that we will talk about later.
A computer language is a language (like English or Spanish, but different) for describing the instructions that you want the computer to do and what data it should use. Later in the course we will learn what computer languages look like and how they are used to create simple software programs.