Coq is a formal proof management system. It provides a formal language to write mathematical definitions, executable algorithms and theorems together with an environment for semi-interactive development of machine-checked proofs. Typical applications include the formalization of programming languages semantics (e.g. the CompCert compiler certification project or Java Card EAL7 certification in industrial context), the formalization of mathematics (e.g. the full formalization of the 4 color theorem or constructive mathematics at Nijmegen) and teaching.
The stable version of Coq is version 8.4. Released in August 2012, it features a uniform modular evolution of the arithmetical libraries, a new proof engine providing bullets, and various improvements of existing features, especially regarding CoqIDE, the tactics, the tactic language, the specification language.