The speaker, Stefan Heinze, discusses Vhost User Block, a user space block IO interface. Vhost User Block allows an application to connect to a software-defined storage system running on the same node. The speaker explains the functionality of block storage interfaces and highlights the benefits and drawbacks of using a user space interface for block IO. Vhost User Block is a faster alternative that eliminates system calls, enhances security, and supports both notifications and polling. The speaker also introduces LibBlockIO, a library that simplifies integration with Vhost User Block, and provides code examples for connecting to a Vhost User Block socket. Additionally, the talk covers features like VDUSE and Ublock that enable the connection of user space block devices to the kernel. Overall, Vhost User Block is recommended for use cases requiring a user space block IO interface for improved performance, unprivileged access, or security.