CosmWasm is a smart contracting platform built for the Cosmos ecosystem. Simply put, it's the Cosmos (Cosm) way of using WebAssembly (Wasm) hence the name.
CosmWasm is written as a module that can plug into the Cosmos SDK. This means that anyone currently building a blockchain using the Cosmos SDK can quickly and easily add CosmWasm smart contracting support to their chain, without adjusting existing logic.
Rust is currently the most used programming language for CosmWasm, in the future, it is possible to have different programming languages like AssemblyScript
The purpose of this documentation is to give a deep dive into the technology for developers who wish to try it out or integrate it into their products. Particularly, it is aimed at Go developers with experience with the Cosmos SDK, as well as Rust developers looking for a blockchain platform.
See CosmWams official document from here.