Containerization is not really a new technology, but it endures because of its efficiency, ease of use, security, and rapid deployment capability. Containers are perfect for isolating applications from on another on a single system. You can containerize just about any service including web, database, application, storage, communication, and so on.
Often, the primary purpose of containers is isolation. Each containerized service runs in its own space on a system. For example, rather than installing a single instance of a web server on a system and using it to serve dozens of websites with virtual host configurations, you can containerize each of the websites and run them individually. The advantage of this approach is simple: If a single instance of a web server crashes, it takes all of the websites with it. Alternatively, if each website is installed in its own container and one of the sites crashes, it only affects that site.
Containers can also be more secure than either traditional virtual machines or standalone physical machines. If a single site is compromised, only that container is compromised and not the entire host system. However, if the host system is compromised, then all of the containers are also compromised. The advantage of containerized applications is that the host system is typically not exposed from a container. In other words, the application doesn't "know" it's running in a container. As far as the application is concerned, it is the only application running on the system. Only the host system is aware of the array of containers it hosts.
We'd like to know, from our list, which is the first application that you containerized.
[ Getting started with containers? Check out this free course. Deploying containerized applications: A technical overview. ]