# Categories

Categories organize products into a hierarchy that buyers can browse.
A path such as Home, Lighting, Table lamps describes where a product belongs in your navigation.

## Build a useful tree

A root category has no parent.
A child category refers to its parent by ID.
Choose a depth that helps a buyer narrow their choice; a category with one child and no useful distinction usually adds another click without helping discovery.

Products can belong to more than one category.
Decide explicitly which nodes should list a product.
Do not assume assigning a leaf also assigns every ancestor.

## Membership and presentation

Set category membership through the product update input.
Use category product reordering for deliberate merchandising order.
Read current membership before submitting a reorder, and use the operation's documented input semantics.
A concurrent synchronization may have added or removed products since the page loaded.

Use the category ID for durable relationships and its slug for a managed storefront URL.
If you change a slug used in URLs, handle redirects in your storefront.

## Storefront behavior

Load category metadata for headings and navigation, then load products with the same store and price context as other product lists.
Membership does not override a product's publication or availability rules.
An empty category can mean that none of its products is visible in the current context.

Use [collections](/concepts/catalog/collections) for a campaign that should not alter the browse hierarchy.
Follow [Organize a catalog](/guides/catalog/organize-catalog) to create both structures.