Hey Umang, Broken links are links or URLs that are not reachable. They may be down or not functioning due to some server error. A valid URL will always have a status with 2xx. There are different HTTP status codes which are having different purposes. For an invalid request, HTTP status is 4xx and 5xx. 4xx class of status code is mainly for client side error, and 5xx class of status codes is mainly for the server response error. We will most likely be unable to confirm if that link is working or not until we click and confirm it.
We should always make sure that there are no broken links on the site because the user should not land into an error page. The error happens if the rules are not updated correctly, or the requested resources are not existing at the server. Manual checking of links is a tedious task, because each webpage may have a large number of links & manual process has to be repeated for all pages. An Automation script using Selenium that will automate the process of checking broken links is a more apt solution.