When learning about virtualisation technologies, what attracted me most were containers because of their easy deployment. Containers (also known as lightweight virtualisation) are tools for isolation, which use namespaces for the purpose. They are a better sandboxing utility, because they generally use more then one namespace and are more focused on creating a whole virtual system instance rather than isolating a single process.
Containers are not a new technology. They have been in UNIX and Linux for decades but due to their increasing use in SaaS and PaaS, they have become a hot topic since they provide the most secure environment to deliver and use these services. They are called lightweight virtualisation because they provide process level isolation, which means they depend on the Linux kernel. Hence, only those instances can be created which use the same base kernel. There are lots of containers available for Linux that have gained popularity over the past few years.