A WordPress website consists of three main elements:

1. The WordPress installation itself
2. The contents of the wp-content directory which includes the themes, plugins and uploads
3. The database, where all the content is stored.

Most WordPress users never come into direct contact with the database and may not even be aware that it's constantly working to populate their site. When WordPress serves up any kind of page, be that the home page, a single post or page or an archive, it's accessing the database to bring up content that editors and administrators have added to the site.

In this series of tutorials I'll look in detail at different aspects of the WordPress database. The series will have nine parts, covering the following:

1. Introduction
2. Relationships between data
3. Content types
4. User data
5. Metadata
6. Taxonomies, categories, tags and terms
7. Taxonomies vs post metadata
8. The options table
9. WordPress Multisite data