Selenium is an open-source tool which automates the testing of web applications. Whereas, Jenkins is also an open source tool which automates building and deploying process of web applications. So, if you run the Selenium testing suite in Jenkins, the result is automatic testing whenever the web application is built and deployed. So, every time a new change is done on the software it will be tested alongside it, before releasing.
Are you interested in learning Selenium? Then do check out the Selenium online training offered by Intellipaat!
Also, have a look at our YouTube video to help you get started.