Make sure you open an external link and PDFs in a new tab/window. It's good website usability.
You’ve found a web page that doesn’t exist. How do feel when that happens?
A well designed error page is supposed to assist and calm your website visitors that nothing is wrong and everything will be okay.
We’ve showcased some of the Good, Bad, and Ugly 404 error web pages.
Investors Business Daily
Bank of America
New York Times