ABSTRACT
A computer is a machine that can perform basic arithmetic operations at a very high speed. It can take logical decisions and select alternative paths depending upon the program logic. It can communicate with the external world via its input/output devices. To get a job done, the computer needs to be instructed through a computer program. A computer program is a set of instructions through which one instructs a computer to perform a specific job. The programming language and its syntax are described by a set of characters. Identifiers are used to specify various objects permitted by the language. An identifier must start with a letter of the English alphabet, may contain other digits and letters or the underscore character, must not contain any special characters or blanks and must have a length not exceeding 63 characters. There are five types of intrinsic data in Fortran. They are integer, real, complex, logical and character.
