Docker is a set of services to OS-level environment virtualization.

It allows you to place ready-to-use software along with its dependencies, such as databases or the necessary libraries in a virtual, separate container. This solution has many advantages and is much more convenient than, for example, full virtualization.

It greatly simplifies the duplication and management of the application between multiple machines. Containers placed on a remote repository can be run on popular cloud platforms such as AWS, Microsoft Azure or on any Linux environment. Additionally, Docker has a built-in Swarm creation tool that merges applications running on multiple devices into one integral system (cluster).

More info:

• What is a Docker Swarm?: https://www.sumologic.com/glossary/docker-swarm/
• Docker Security Cheat Sheet: https://cheatsheetseries.owasp.org/cheatsheets/Docker_Security_Cheat_Sheet.html
• Wikipedia: https://en.wikipedia.org/wiki/Docker_(software)