The Container ecosystem spans from spawning a process into an isolated and constrained region of the kernel at bottom layer, building and distributing images just above to discussions on how to schedule a fleet of containers around the world at the very top. While the top layers get all the attention and buzz, this session will base-line the audiences' understanding of how to execute containers. The talk will briefly recap the history of containers and containers in HPC and describe the challenges we faced and how the community overcame them; eventually converging towards a sustainable model to run HPC application at scale using containers. By attending this sessions viewers will come to understand that HPC runtime engines are not far apart anymore and what to look out for when adopting HPC containers in 2021. We'll also poke at the next layer up - Image build and distribution - to describe the challenge after we picked the runtime engine.