What is Jenkins and why it is used? code example

Example 1: how to use jenkins

Jenkins is
1) Open source automation server
2) Helps to automate the non-human part of
the software development process
3) Allows continuous integration
5) In my company Port is 8081 localhost
 To run my project in Jenkins
1) I need  to Login Jenkins account
2) I need to Create freestyle project
3) after that Install plugins -cucumber report and git
4) Under source code management I choose git and past git url
5) I Build trigger and I choose to build periodically
6) Invoke top-level maven
1. Maven version; MAVEN_HOME
2. Goals; clean verify -
Drunner=smoke_runner.xml
7) Under post-build actions
1. Choose cucumber reports
2. Choose editable email notify
8) Editable email notification
1. Attach build log; choose build log
2. Click advanced settings
9) Failure-Any
1. Click advanced
2. Recipient list - email address who will
receive the report. Add comma if multiple
3. Click add trigger - like failure always
4. Attach build log; select attach build log
5. Save
10) Final Step
1. Click build now and test will run and
gives your cucumber report

Example 2: what is jenkins

Jenkins automates building, testing,
reporting, packaging, staging, deploying
the application by using plugins.
Jenkins offers a simple way to set up a
continuous integration or continuous 
delivery environment for almost any 
combination of languages and source code
repositories using pipelines, as well as
automating other routine development tasks.
While Jenkins doesn’t eliminate the need
to create scripts for individual steps, 
it does give you a faster and more robust
way to integrate your entire chain of build,
test and deployment tools than you can 
easily build yourself.