What is Gossamer?
Gossamer is an implementation of the Polkadot Runtime Environment written in Go. The Polkadot Runtime Environment is a modular, customizable framework for building blockchains. It has a swappable WASM runtime (ie. state transition function) that can be replaced even after the blockchain has launched without hard forks. It also has a generic extrinsic and block format which are specified in the runtime. The runtime can be written in any language that compiles to WASM.