Your site might get lower search engine (Google) rankings — that is, appear lower in search engine results — if your site has broken links in it. Broken links are when a link on your site (which probably worked when you first created it) no longer works, and displays an error or “page not found” message.
This might happen if you linked to a page of another site, which subsequently took down that page of their site, or changed the URL of that page. It frequently happens for our clients when they remove old PDFs and images from the Media Library without removing the links in posts or pages to those media files. (Remember, when you insert an image, you are creating a link to that media file.)
To find broken links on your site, use this free online Broken Link Checker.
Once you have identified the broken links, then the next step is to fix them by either updating to the new URL (if there is one) or removing the broken link.