{{language|Fortran |strength=strong |safety=safe |compat=nominative |checking=static |gc=no |LCT=yes |tags=fortran |bnf=}}{{language programming paradigm|Imperative}}{{Language programming paradigm|Procedural}}{{Language programming paradigm|Object-oriented}}{{Language programming paradigm|Concurrent}} Fortran is the oldest programming language still in widespread use. The language has evolved considerably since it was first released in 1957. Fortran was original developed for scientific and engineering applications, and remains especially suited to numeric computation and scientific computing. By convention, versions before Fortran 90 are spelled with all uppercase letters (e.g. FORTRAN IV, FORTRAN 66, FORTRAN 77), while starting with Fortran 90, the mixed case spelling is used (i.e. Fortran 90, Fortran 95, Fortran 2003 and [ Fortran 2008]). The most recent standard is [ Fortran 2018] (ISO/IEC 1539-1:2018).

FORTRAN 77, being quite old, lacks almost everything one expects from a modern programming language. It uses a fixed-length line and column oriented line format which was motivated by punch cards. Due to its age, and since FORTRAN compilers generally gave very good performance for numerical code, a lot of code, especially scientific code, was written in FORTRAN. Also, for quite a while there was no free Fortran 90 compiler, which also caused a lot of FORTRAN 77 code to be written even quite some time after Fortran 90 was standardized. Because of the large body of code written in FORTRAN 77 it remains relevant today. Indeed, every modern Fortran compiler still accepts FORTRAN 77 code.

Fortran 90 was a major revision of the language. It introduced a new free-form source code format, modern programming language features like modules, pointers and user-defined types, an improved type system for built-in types and superiour built-in array handling. Newer Fortran standards (Fortran 2003 and Fortran 2008) added further modern features, like support for [[object oriented programming]], [[inheritance]], [[polymorphism]], [[parallel processing]], and [[interoperability]] with the [[:Category:C|C programming language]].