What kind of content to add to a 404 page?
It’s really up to you, and depends on your website, the type or profile of your visitors, and the way you address them.
A 404 error page can be limited to a simple message, be a way to truly express your creativity and engage your visitors, and can help to attract new ones; make a truly original error page that stands out, and it’ll get people talking about it!
It’s a good idea to include useful navigational links in the page, such as one to your site homepage, or a browser history “go back” link so visitors can click it to return to the page from which they arrived.
You can even use it to add a search box for your site content, to help wayward visitors help find what they’re actually looking for.