Over time, external links on your website can become dead. Maybe you reviewed a product and then 3 months later the owner decided to remove it and close down the site. Maybe you have a comment from someone and they left their website URL but they have since closed their website.
Whatever the reason, it does happen, and it's not good to have the dead links on your website because it shows Google and your visitors that you are not taking care of things. But you won't know about these dead links unless you check for them.
Go to http://www.brokenlinkcheck.com/
Enter your website URL:
Select "Report all occurences of each dead link":Hover your mouse over url and you will see the URL of the page on your website where the dead link is:Then you can edit that post/page to remove that dead link. In the above instance, I know that it is on a comment, so I can go in and remove that URL from the comment.