There are several varieties of computer programs, but the ones most of us are familiar with are the application software. An application is software with a specific use, such as writing, dealing with numbers, organizing large amounts of data, etc. Popular types of applications software include word processors, database managers, spreadsheets, graphics applications, money managers, and games. Other types of computer software include utilities (programs designed to tune the performance of the computer), and system software (basic programs, such as DOS , windows ,UNIX , Linux , MAC which are required to operate the PC).
Applications software are created with the help of a programming language (such as BASIC or C). A program is a set of instructions that tells the computer how to perform a task. Most programs look somewhat like broken English; the actual words and the structure of each instruction depends on which programming language is being used. Following the rules of a particular programming language, a programmer writes the step-by-step instructions that tell the computer exactly what to do. Anyone can write a program, but he must learn the rules of a particular programming language first. Although most applications are written by teams of people working for big companies like Microsoft, there is still room for the tinkerer who writes programs at home in his or her spare time.
For example, in 1978, Dan Bricklin, a Harvard Business School student, developed an idea for a type of program that could easily be used to perform complex business analyses. With his partner, Bob Frankston, he created the first "spreadsheet" program called VisiCalc. Actually, by most accounts, VisiCalc was the first modern computer application ever. Early applications were very complicated to use and required a thorough knowledge of their commands to perform even simple tasks. Today's applications are much easier to use, very intuitive in operation, and friendly to the eye. The total number of commercial applications now available is well into the thousands. However, some large and small companies still write their own private applications to handle all types of jobs, including payroll, personnel, security, facilities management, and accounting.