Kernighan & Ritchie (K & R) C Standard
The first edition of "The C Programming Language" book by Brain Kernighan &Dennis Ritchie was published in 1978 .This books one of the most successful computer science books and has served as an informal standard for the C language for many years .This informal was know as 'K & R C'.
ANSI C/Standard C/C89 Standard
In 1983,a technical committee was created under the American National Standards Institute (ANSI) committee to establish a standard specification of C.In 1989,the standard proposed by the committee was formally approved and is often referred as ANSI C,Standard C or sometimes C89.
ISO C/C90 Standard
In 1990,the international Organizational Standardization (ISO) adopted the ANSI C Standard after mirror modifications . This versions of standard is called ISO C or sometimes C90.
After the adoption of the ANSI standard , the C language specification remains unchanged for sometime,whereas the language C++ continued to evolve . To accommodate this evolution of C++,a new standard of C language that corrected some details of ANSI C standard and added more extensive support to it was introduced in 1995 . The Standard was published in 1999 and is known as C99.The C99 standard has not been widely adopted and is not supported by many popular C Compilers.