Keywords and Categories defines the available categories for organizing pages. Categories are storage-based and determine where pages are stored and how they're managed during upgrades.
Keywords and Categories is part of Page Metadata Documentation in
"_comment_systemCategories": "System category definitions with storage location mapping",
Keywords and Categories are validated by ValidationManager
Keywords and Categories are Managed through ConfigurationManager by Administrators.
Refer to system-category
refer to User Keywords
Refer to System Keywords