A computer program<\/a>, from one perspective, is a sequence of instructions that dictate the flow of electrical impulses within a computer system<\/a>. These impulses affect the computer\u2019s memory and interact with the display screen, keyboard, mouse, and perhaps even other computers across a network in such a way as to produce the \u201cmagic\u201d that permits humans to perform useful tasks, solve high-level problems, and play games. One program allows a computer to assume the role of a financial calculator, while another transforms the machine into a worthy chess opponent. Note the two extremes here:<\/p>\n So well is the higher-level illusion achieved that most computer users are oblivious to the lower-level activity<\/a> (the machinery under the hood, so to speak). Surprisingly, perhaps, most programmers today write software at this higher, more abstract level also. An accomplished computer programmer can develop sophisticated software with little or no interest or knowledge of the actual computer system upon which it runs. Powerful software construction tools hide the lower-level details from programmers, allowing them to solve problems in higher-level terms.<\/p>\n The concepts of computer programming are logical and mathematical<\/a> in nature. In theory, computer programs can be developed without the use of a computer. Programmers can discuss the viability of a program and reason about its correctness and efficiency by examining abstract symbols that correspond to the features of real-world programming languages but appear in no real-world programming language. While such exercises can be very valuable, in practice computer programmers are not isolated from their machines. Software is written to be used on real computer systems. Computing professionals known as software engineers develop software to drive particular systems. These systems are defined by their underlying hardware<\/a> and operating system<\/a>. Developers use concrete tools like compilers, debuggers, and profilers. This chapter examines the context of software development, including computer systems and tools.<\/p>\n <\/p>\n","protected":false},"excerpt":{"rendered":"\n