Every page, post, and category in WordPress has a unique ID. This ID is used behind the scenes to help WordPress keep things organized.
Here’s how you can find it:
Find a Page or Post ID
- Go to your WordPress dashboard.
- Click on Pages or Posts, then choose the one you want to check.
- Once you open it in edit mode, look at the URL in your browser.
You’ll see something like this:...post.php?post=1234&action=edit

In this case, 1234 is the ID of the post or page.
Find a Category or Tag ID
- Go to Posts > Categories (or Posts > Tags).
- Click the category or tag you want to check.
- Look at the URL when the edit screen opens.
It will look something like this:...edit-tags.php?action=edit&taxonomy=category&tag_ID=21

Here, 21 is the ID of that category.
That’s it! Just check the browser link when editing, and you’ll always find the ID you need.