In 1.30.1 theme version, we have made the IDs visible in admin section. Starting this version you do not need any additional plugins to see IDs.
We added this for properties, taxonomies, agents and posts
The Ids are mostly used in shortcodes like Recent Items, Featured Agent. Featured Property or Recent Items for posts and many others.
Now you can find them in admin in lists:
These is the IDs that needs to be added in shortcodes.
Also there are plugins available to see Ids easier like Reveal Ids.