The inert attribute/property allows web authors to mark parts of the DOM tree as inert:

When a node is inert, then the user agent must act as if the node was absent for the purposes of targeting user interaction events, may ignore the node for the purposes of text search user interfaces (commonly known as “find in page”), and may prevent the user from selecting text in that node.

Furthermore, a node which is inert should also be hidden from assistive technology.

I just recently learned about the forthcoming inert attribute and it’s really interesting. I highly recommend you read the Explainer.