The wp_terms table is used to store a WordPress website's categories, tags, and custom taxonomy terms. More details about terms are stored in wp_term_taxonomy and wp_termmeta tables.
Columns
term_id: This column stores the unique identifier for each term in the wp_terms table. Each term, whether it's a category, tag, or custom taxonomy, is assigned a unique term_id (an integer). It is used as a primary key for this table and referenced in wp_term_taxonomy table, which contains taxonomy and hierrarchy (parent/child) information for individual terms.
name: Term name is the human readable "nice" name or title for the term. For example, if the term is a category, the name might be "Recipes". If the term is a tag, the name might be "Healthy Eating". The name value is displayed on the front-end of the website to help visitors navigate and organize content, or as the h1 heading on the category or tag page.
slug: This column stores the URL-friendly "slug" for the term. The slug value is a lowercase version of the name with spaces replaced by hyphens. For example, if the name value is "Healthy Eating", the slug value might be "healthy-eating". The slug is used in the URL when displaying content associated with the term.
term_group: The term_group value is used to sort terms and group them together. For example, if a website has multiple categories for different types of cuisine, you might want to group them together under a "Cuisine" term group. In this case, all categories related to cuisine would have the same term_group value. By default, the term_group value is set to 0, which indicates that the term is not part of a group.
Example
For example, let's say you have a website about healthy eating and you want to organize your content by categories such as "Recipes", "Tips & Tricks", and "Food News".
You create new terms for each of these categories in the wp_terms table. For the "Recipes" category, you might set the name column to "Recipes", the slug column to "recipes", and the term_group column to 0 (since this category is not part of a group).
When you create a new post and assign it to the "Recipes" category, the term_id value for the "Recipes" term would be stored in the wp_term_relationships table along with the post_id of the post. This allows WordPress to query the database and retrieve all posts associated with a particular category.
SQL Schema
CREATE TABLE `wp_terms` (
`term_id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
`name` varchar(200) COLLATE utf8mb4_unicode_ci NOT NULL DEFAULT '',
`slug` varchar(200) COLLATE utf8mb4_unicode_ci NOT NULL DEFAULT '',
`term_group` bigint(10) NOT NULL DEFAULT 0,
PRIMARY KEY (`term_id`),
KEY `slug` (`slug`(191)),
KEY `name` (`name`(191))
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;