C11 is a standard for the C programming language. It replaces the previous C99 standard. C11 added type-generic expressions, alignment support, static assertions, library support for multithreading and unicode as well as multiple other language and library fixes and additions.
C11 is a standard for the C programming language. It replaces the previous C99 standard. C11 introduces a number of features to the language, most notably a detailed memory model focussed on multi-threaded applications. New keywords _Generic, static assertions, library support for multithreading and unicode and more.
More details can be found on the wikipedia C11 entry.
More technical details can be found on the open standards organization site, too
