What is Site Markers and How to use them in Power Pages
Site markers are configurable, named value that points to a web page on your power page/portal website that is accessed in code in place of a hard-coded URL. Most of the times you might be using URLs in some links element which are hard coded or static. But as a best practice and better management, you need to use Site markers which will help you to dynamically use the URL using Site markers.
If in any case the URL is need to be updated, then no need to update code, you just need to update the Site marker and the page will be automatically using the Site marker to new URL.
How to create a Site Marker
To create a site marker, open the Power Page Management model driven app and navigate to Site Markers link from sitemap and click new option. provide Name, Website and target webpage.
You can now add a link using HTML anchor tag with href using below code in web page or web template.
<a href={{ sitemarkers['Page Not Found Page Marker'].url }}>Not Found Link</a>
You can also call it using Liquid code as below.
{{ sitemarkers["Page Not Found Page Marker"].url }}
Now save, clear the cache. then refresh the portal to test.
Hope this helps.