The study of data models, their properties, and their appropriate use is one pillar of computer science. A second, equally important pillar is the study of algorithms and their associated data structures. We need to know the best ways to perform common tasks, and we need to learn the principal techniques for designing good algorithms. Further, we need to understand how the use of data structures and algorithms fits into the process of creating useful programs. The themes of data models, algorithms, data structures, and their implementation in programs are interdependent, and each appears many times throughout the book. In this section, we shall mention some generalities regarding the design and implementation of programs. The Creation of Software In a programming class, when you were given a programming problem, you probably designed an algorithm to solve the problem, implemented the algorithm in some language, compiled and ran the program on some sample data, and then submitted the program to be graded.

In a commercial setting, programs are written under rather different circumstances. Algorithms, at least those simple enough and common enough to have names, are usually small parts of a complete program. Programs, in turn, are usually components of a larger system, involving hardware as well as software. Both the programs and the complete systems in which they are embedded are developed by teams of programmers and engineers; there could be hundreds of people on such a team.

Software The development of a software system typically spans several phases. Although development process these phases may superficially bear some resemblance to the steps involved in solving the classroom programming assignment, most of the effort in building a software system to solve a given problem is not concerned with programming.