This lets you know that the source page contains a broken link to the target resource. Note that offsite resources also appear red if the links to them are broken. In the example below, the Home Page contains a broken link to Earth. The link can be fixed by opening the source file for the Home Page and editing the broken link for Earth. You can accidentally break links as you edit HTML files, move files, or perform other maintenance tasks.
Broken links can occur for many reasons, as shown in the following table.
The resource a link points to is renamed, moved, or deleted. Search for the broken link, look at the Link URL column, and correct the error. The HREF attribute contains an error. View the HREF attribute and correct any errors that you find. For details, see Verifying Links.