The Broken Link Checker loads one page, collects the unique links on it and requests each one. It reports how many links it checked and how many are broken, and lists every broken link with its status code, anchor text and URL. A link counts as broken when it returns an error status of 400 or higher, or does not respond at all.
Updated
The headline is either No broken links or a count. Under it you see how many links were checked and how many broke.
Broken links are listed in a table with the status, the anchor text and the URL. A link with no text shows as (no text).
A 404 or 410 means the page is gone. A 500 or other 5xx means the other server had a problem, which can be temporary, so run the check again before you act on it. No response means the request failed or took longer than 8 seconds.
A 401, 403 or 429 can come from a site that refuses automated requests. Open the link in a browser. If it loads, leave it alone.
The tool reads the links in the HTML the server sends, so links that JavaScript adds after the page loads are not included. It checks up to 60 unique links per page, 6 at a time, and tells you when it stopped at 60. It looks at one page only, not the whole site.
Peak Answer runs checks like these every week, then writes the content and gets the placements.