How To Add Meta Boxes and Custom Fields To Posts in Gutenberg

Custom fields provide a way to assign extra information to website content. These bits of information are usually known as metadata.

Metadata is information about information. In the case of WordPress, it’s information associated with posts, users, comments and terms.

Given the many-to-one relationship of metadata in WordPress, your options are fairly limitless. You can have as many meta options as you wish, and you can store just about anything in there.

—Plugin Handbook

Here are some examples of metadata you can attach to a post using custom fields:

• The geographic coordinates of a place or real estate
• The date of an event
• The ISBN or author of a book
• The mood of the day of the author of the post