Broken links can be easily avoided. When creating a hyperlink to another page, it is important to use the page asset ID rather than the page URL:
When a page gets moved or archived, the URL changes and the user will not be able to reach the information they are searching for. However, the asset ID does not change. This way, if a page is moved the hyperlink will still link to the page. If you link to a URL you will get a broken link when the page is moved.
If a page is deleted, you will not be alerted so it is important to review your web content and links regularly.