Jenkins is an open-source tool to perform continuous integration and build automation. It has the same purpose as any other continuous integration tool, such as Bamboo (CirclCI), which tests the code as early as possible in the development stage.
In Jenkins, you define the set of instructions to deploy your application over different application environments (development, pre-production stage, and so on).
Before going forward to set up a job (basically, a project) in Jenkins, and learn about the Jenkins plugins, let's first set up Jenkins and configure it as per our requirements.