The computer can't understand English or any other spoken language for that matter. It actually doesn't understand anything. Computers can't think. They merely process series of electrical impulses which can be interpreted as logical yes/no choices. This makes it seem like the computer isn't very useful. But it is hard to imagine a world without the aid of computers. So how do you communicate with something that only understands yes and no?
The answer to this question is based on the fact that most people use the computer for the same type of thing--to do basic calculations for them at high speeds. Any human of reasonable intelligence could do whatever their computer does--it would just take much longer. For this reason, a standard set of code has been defined to translate sets of these yes/no bits into text, numbers, and symbols. The most common of these codes is the ASCII character set since it contains all letters of the alphabet (upper and lower case), all ten digits, and all punctuation. This character set can be used to write lists of commands for the computer to carry out. These lists are called programs.
But what about the people who need or want to use a computer that don't know how to write a program? They just want to use the programs of other people. But since they don't know how to write programs, they won't know how to run the other programs, or how to get to their data files. For this reason, operating systems have been developed. Operating systems are collections of programs and utilities that help people navigate their way around their computer. On IBM compatible PCs, the most common operating system is DOS (Disk Operating System)/Windows. However, there are other, more specialized operating systems for PCs as well. OS/2 Warp is used a lot in businesses. UNIX, also used a lot for businesses, supports multiple users on one system. On other systems such as Macintoshes, a purely graphical operating system called System 7.5 (or other version number) is used.
The anatomy of a computer
The combination of programs and operating systems are known as software. Software is the part of the computer that you can't see, but is essential for the computer to operate usefully. It can easily be copied, moved, or transferred great distances in moments. It is made up of bits instead of atoms as hardware is. This gives it many advantages. For example, at a library, there may be one, two, or possibly three copies of a book. If all of the copies get checked out at once and another person wants to check it out, they have to wait for one of the other copies to be returned. The atoms which make up the book must be present for the information to be available. However, in a digital library, it is only necessary to have one copy of the information, and many, many people all over the world can view the information at the same time.
