FORTRAN 66, a seminal programming language in computing history, was originally the foundation for scientific and technical applications. It was developed in the late 1950s and paved the way for high-level languages by allowing programmers to express complex mathematical equations and algorithms without having to go deeply into machine-level code. This transformed how engineers and scientists addressed computer issues, and FORTRAN 66 became a standard in many industries for decades.

FORTRAN 66 presented a structured approach that helped optimize performance in systems with limited resources. Its popularity in industries including as aerospace, defense, and weather forecasting was unparalleled because the language provided dependability and speed for numerical computations. Despite its sturdy design, FORTRAN 66 began to lose popularity as newer, more flexible languages appeared. Languages such as C and later Python provide greater versatility, allowing developers to work on a broader range of applications.

FORTRAN 66's inflexible structure, while appropriate for some applications, gradually became a limitation. As computing advanced, the desire for languages that supported more dynamic operations increased. This movement was prompted by developments in hardware and software, as well as a growing demand for user-friendly, general-purpose languages. The FORTRAN syntax, while powerful for computation, was viewed as cumbersome in comparison to newer alternatives that made debugging and code maintenance easier.

By the 1980s, FORTRAN 66 had been gradually phased out, with newer versions such as FORTRAN 77 taking its place, albeit even these battled against modern languages. FORTRAN's legacy is still substantial, notably in the field of high-performance computing, but it is no longer the first choice for most developers. The extinction of FORTRAN 66 represents the unavoidable march of technology, as programming languages evolve or fall behind the changing demands of the computer industry.