Your 404 page is shown to users when a URL/page can't be found (perhaps it's a product you've now deleted, or they mistyped the URL). 404 pages are never indexed by search engines, so there's no SEO value to their title and description. Creating a descriptive title and description for 404 pages makes it clear to human users the page they were trying to get to can't be found.
Follow the steps to create a descriptive title and description for your 404 page.
- Copy the 'Title template' below
- Paste it into the '404 title template' in Plug in SEO Plus
- Copy the 'Description template' below
- Paste it into the '404 description template' in Plug in SEO Plus
- Press 'Save and preview'
404: Page Not Found - %% shop.name %%
The page you requested can't be found, please visit %% shop.domain %% instead