The document discusses unikernels, which are specialized virtual machines composed of a single application statically compiled with its dependencies. Unikernels offer benefits like improved performance and security compared to traditional virtual machines. UKL is presented, which is an approach to building unikernels using the Linux kernel in order to gain support for existing Linux drivers and tools. Testing shows UKL can provide performance improvements over generic Linux, particularly for applications like Redis and Memcached.