What is the Common Language Specification (CLS)?

The CLS contains constructs and constraints which provides a guideline for library and compiler writers.

Any language that supports CLS can then use the libraries due to whic the languages can integrate with each other.

The CLS is a subset of the common type system.

The CLS is important to application developers because when developers design publicly accessible APIs per the CLS, those APIs are easily used from all other programming languages that target the common language runtime.