Where is the page ID?

Grab a plugin called Reveal IDs for WP Admin (https://www.ads-software.com/extend/plugins/reveal-ids-for-wp-admin-25/). It will show the category and page IDs on their respective tables.

Thank you for this. Actually I discovered also that when you edit a page, the ID appears in the url bar.

But does anyone know why the wordpress software doesn’t display it in the page editor?