What a 404 means
The code 404 tells browsers and search engines that the page was not found. It is normal for some addresses to produce it. The trouble comes when important pages return it by mistake, or when a missing page shows a friendly message but sends the wrong signal to search engines.
What to put on the page
Keep the site header and navigation so people are not stranded. State plainly that the page was not found, without jargon or jokes that blame the visitor. Offer a search box if your site has more than a handful of pages, plus links to your most requested pages: services, contact, and the home page.
Include a phone number or contact link. Someone who arrived looking for a quote may simply call. A short line such as If you followed a link here, tell us and we will fix it makes the page useful to you too.
Return the right status code
A custom page must still send a real 404 status. When a page displays a not found message but returns a normal 200 code, search engines call it a soft 404 and may waste crawling time on it. Test with a header-checking tool or the Network tab in your browser developer tools.
Do not redirect all missing pages to the home page. That confuses people and is treated much like a soft 404.
Set it up on your platform
WordPress themes usually include a 404 template that you can edit, or a plugin can manage it. Hosted builders typically have a not found page setting. On servers, an error document directive points to your custom file.
Keep the page light and quick, with the same fonts and layout as the rest of the site. Avoid heavy animation or large images.
Find and fix real broken links
A custom page does not repair the cause. Check Search Console reports for pages it could not find, review analytics for visits to the 404 template and crawl your own site for broken internal links. Where an old page has a clear replacement, add a 301 redirect. Where nothing replaces it, let it return 404.
Do this check each quarter. It takes little time and keeps visitors from hitting dead ends repeatedly.
Examples of wording that works
Plain wording beats cleverness. A heading such as We cannot find that page is clear. Follow it with one sentence about what may have happened: the link may be old or mistyped. Then give two or three buttons: Go to home page, See our services, Call us. If your business has a seasonal offer or booking link, it is reasonable to feature it, as long as it does not crowd out the way back.
Avoid blaming language, avoid ads and avoid forms that ask for a lot of information. The page should help someone move on in a few seconds.
Common questions
Do 404 errors hurt my SEO?
A normal number of 404s does not hurt. Problems come from broken internal links, or from deleted pages that still have backlinks or traffic.
Should a deleted page return 404 or 410?
Either is understood. A 410 says gone for good, but a 404 is fine for most small sites.
Can I add a search box without a plugin?
Many themes and builders include one. If not, a simple list of key links works.
This guide is general information. Search engines change how they work and their guidelines; check Google's current documentation for your situation. Nobody can guarantee a ranking.