DuckDB has introduced Quack, a client-server protocol that allows multiple instances to communicate with each other, enabling use cases such as concurrent writers and remote data access. Quack is built on top of HTTP and is designed to be fast and efficient. The protocol allows for bulk data transfer and small transactions, and is optimized for low latency. Quack can be used with DuckDB's existing features, such as DuckLake, to enable new use cases.