A Broken Link is a link that does not lead to another page and results in a 400's or 500's error (See: Status Codes).
Reasons for broken links are programming errors, temporarily unavailable websites or a change in the address of the website to which the link leads. Broken links reduce the quality of the website and make the crawler's work more difficult. For these reasons, a website with broken links is penalized by search engines and will not rank high in search results. Therefore, these problems should be located and fixed as soon as possible.
To be able to analyze broken and forwarded links, a crawl must first be created. You can learn how this works here. Once the crawl is complete, you can navigate to Link Analysis > Broken and Redirected Links.
At the bottom of the page is a list of all URLs that point to broken links.