The "page not found" page helps

Everybody reaches a 404 eventually: an old link, a typed address, a printed leaflet. What happens next is entirely up to you, and the default supplied by most hosts — a white page reading "Not Found" in Times New Roman — sends the visitor back to the search results, which is to say to a competitor.

We can check that missing pages answer 404 rather than pretending to be fine (indexing.status does), but whether the page is any use takes a person to look.

Source: Google: prevent soft 404 errors.

Visit an address on the site that certainly doesn't exist and look at what you get. It should:

- look like the rest of the site, header and menu included; - say plainly that the page isn't there, without blaming the visitor; - offer the search box and a few of the most-wanted pages; - still answer with the 404 status, not 200 — a friendly page that claims to be fine is worse than an unfriendly one, because search engines then index it.

Tick this when the page does all four.