Docker and containerization technology is not a trend new topic, it has been around for decade. We have seen the term within a project called OpenVZ which is container-based virtualization for Linux released back in 2005. In this project, you were able to create multiple isolated, secure containers to run them inside same server. Around 2005, we have heard about another project called Jails developed by FreeBSD team. Jails let you put applications and services into one Jail (container). Why has docker became popular even if there are containerization technologies exist more than a decade?
Docker is an open source project for building, shipping, and running distributed and scalable applications with its dependencies. It helps programmers, operation engineers, and development teams to have common toolbox without knowing hard core logic of Linux containerization stuffs like chroot. You can see lots of articles about docker best practices and real life production scenarios here.