URL redirects of webpage

Basically, it’s a canonical redirection.

In WordPress, there is a function named redirect_canonical, or there’s a canonical redirect feature which:

1. Provides an SEO enhancement which prevents penalty for duplicate content by redirecting all incoming links to one or the other.

   For example, if one visits a single post page where the default or “non-pretty” URL looks like https://example.com/?p=1 (1 is the post ID) and if “pretty links/URLs” (i.e. permalinks) are enabled on the site, then WordPress would redirect the request (or your browser) to the proper post permalink which may look like https://example.com/hello-world/ (hello-world is the post slug).

   And that is to prevent search engines from treating the same post as two posts having a duplicate content, or that without the redirection, search engines would see two different URLs with the exact same content (despite the page source/HTML are different), hence a duplicate content penalty would incur for the site.

   Other examples: ( Note: I intentionally omitted the protocol part (e.g. https://) )

   | Type               | Sample Default URL            | Sample Permalink (or "Pretty URL")  |
   |--------------------|-------------------------------|-------------------------------------|
   | Single Pages       | example.com/?page_id=2        | example.com/sample-page/            |
   | Category archives  | example.com/?cat=1            | example.com/category/uncategorized/ |
   | Tag archives       | example.com/?tag=my-tag       | example.com/tag/my-tag/             |
   | Post type archives | example.com/?post_type=my_cpt | example.com/my_cpt/                 |
   

2. Attempts to find the correct link when a user (or you) enters a URL that does not exist based on exact WordPress query.

   I.e. If a 404 (“not found”) error was encountered, WordPress would try to resolve it by “guessing” what should be presented to the user, before eventually showing a 404 error page.

And in your case, that second point is likely what’s happening — you don’t have a page with the slug contact, so WordPress tries to find one which contains contact in the slug, and because you do have one (contact-us), that explains why www.mywebsite.com/contact redirects to the www.mywebsite.com/contact-us page.

And actually, that guessing part is quite cool.. in that if you’re lazy or don’t remember the exact slug, you could just type part of it. 🙂 But that’s just my opinion.

Hope this (revised) answer helps you!