A high-level programming language developed by Dennis Ritchie at Bell Labs in the mid 1970s. Although originally designed as a systems programming language, C has proved to be a powerful and flexible language that can be used for a variety of applications, from business programs to engineering. C is a particularly popular language for personal computer programmers because it is relatively small -- it requires less memory than other languages.
             The first major program written in C was the UNIX operating system, and for many years C was considered to be inextricably linked with UNIX. Now, however, C is an important language independent of UNIX.
             Although it is a high-level language, C is much closer to assembly language than are most other high-level languages. This closeness to the underlying machine language allows C programmers to write very efficient code. The low-level nature of C, however, can make the language difficult to use for some types of applications.
             Pronounced lee-nucks, A freely-distributable implementation of UNIX that runs on a number of hardware platforms, including Intel and Motorola microprocessors. It was developed mainly by Linus Torvalds. Because it's free, and because it runs on many platforms, including PCs, Macintoshes and Amigas, Linux has become extremely popular over the last couple years.
             Another popular, free version of UNIX that runs on Intel microprocessors is FreeBSD.
             A program interface that takes advantage of the computer's graphics capabilities to make the program easier to use. Well-designed graphical user interfaces can free the user from learning complex command languages. On the other hand, many users find that they work more effectively with a command-driven interface, especially if they already know the command language.
             Graphical user interfaces, such as Microsoft Windows and the one used by the Apple Macintosh, feature the following basic components:
              pointer : A ...