What is CLS (Common Language Specification)?
CLS provides the set of specification which has to be adhered by any language writer/compiler writer for the .Net framework. This insures interoperability. Or The Commom Language Specification defines a set of rules that enables interoperability on the .Net platform. These rules serves as a guide to third-party compiler designer and library builders. The CLS is the subset of CTS and there for the language supporting the CLS can uses others class libraries as if they azre thier own. Application Program Interface (APIs) that are designed following the rules of CLS can easily be used by all the .Net languages.