C programming language was developed in 1972 by Dennis Ritchie at bell laboratories of AT&T (American Telephone & Telegraph) in the U.S.A. 

ANSI C or C89 standard: first standardized specification for C language and was developed by American National Standards Institute in 1989. 

C90 (ISO C 1990) : more or less identical to C89, but in an ISO document.

C99 standard was published in 1999.

C11 (formerly C1X) standard was released in 2011. The formal document describing the C11 standard is called ISO/IEC 9899:2011. 

C18 is the informal name for ISO/IEC 9899:2018.