To take full advantage of all the WordPress template tags and functions it is often required to use post IDs and category IDs. These values can be found conveniently in the WordPress admin area, without needing to refer to the database.
Finding a WordPress Post ID
To find the ID of a particular post or page in the admin area, you will first need to navigate to Posts > Edit or Pages > Edit as applicable. If you then roll over the link to edit the corresponding page or post, your browser's status bar will display the url for editing that page. This url will include 'post=' and then the ID (e.g. in the image below the post ID is 218).
Finding a WordPress Category ID
To find the ID of a category in the admin area, you can will first need to navigate to Posts > Categories. From the list of categories that will then be visible on the right, you can then roll over the Edit link for the category corresponding to the ID that you need. In your browser's status bar the url for editing that category will then be visible. This url will include 'cat_ID=' and then the category ID (e.g. the category ID for the 'Business' category in the example below is 4).
Finding a link category ID is a very similar process - the ids in this case are available via Link > Link Categories.