rel="search" attribute value specifies that the linked page can be used to search relevant content in the current page.
rel="search" on an <a> element.
This link is a Google search query with a filter for the current site.
To discover more: <a rel="search" href="https://google.com/search?q=site:dofactory.com" target="_blank">Search here</a>.
The rel attribute defines the relationship between the current page and the linked page.
rel="search" value specifies that the linked page is designed to search the current page for related content, resources, and more.
<tagname rel="search" />
These elements accept the search value on the rel attribute.
|<a>||Specifies an anchor link -- see example above|
|<area>||Creates clickable areas inside an image map.|
|<form>||Specifies an HTML form.|
|<link>||Links a resource to the current page|
Here is when rel support started for each browser: