FORTRAN 77 is a high-level programming language that was developed in the 1970s as an update to earlier versions of FORTRAN. It is particularly known for its use in scientific and engineering applications due to its ability to handle complex mathematical calculations efficiently. The language introduced several features, such as structured programming constructs and improved input/output capabilities. While it has largely been succeeded by more modern languages, FORTRAN 77 remains in use today, especially in legacy systems and applications that require high-performance computing.