Categories form a tree: any category can sit inside another.
Uncategorized cannot be deleted
Each site has one system category that acts as the fallback. Its delete button does not work, and its slug and position are locked.
The reason is that a product should never exist with no category at all; this one guarantees there is always somewhere to put it.
Deleting a category does not delete products
When you delete a category:
- products for which it was the primary category move to Uncategorized;
- its child categories are not deleted — they move up to the top level.
So removing a branch never takes the branches beneath it with it.
The slug is the category page's address
A slug is unique across the site and appears in that category's storefront address. Changing it breaks the old address, so it is best left alone once published.
Leave it empty and it is generated from the name; for a non-Latin name it is worth writing a Latin slug yourself.
A product can sit in several categories
A product can be linked to any number of categories, but one of them is shown as the primary category on the product card.