Hi,
It is not mandatory to use the All category, you can set the needed category for the product, for example if we are running a retail store with fruits and vegetables, i can classify my products into two categories and assign the needed category for the product.

For apple fruit category and for onion vegetable category. Just to categories the product and some of  accounting/inventory related information's is configured in the category.

Thanks

Hi,

In Odoo, the product category "All" is the top-level category in the hierarchy of product categories. It serves as the parent category for all other product categories. The primary purpose of having an "All" category is to provide a structured and hierarchical organization for products, making it easier to manage and navigate the product catalog.

The "All" category is the root category under which all other categories (such as "All/Component", and "All/Saleable") are organized. This hierarchical structure helps in categorizing products more granularly and logically.

Configurations set at the "All" category level can be inherited by all subcategories. For example, accounting properties, routes, or other default settings defined at this level apply to all products within the hierarchy unless overridden by subcategories.

Ease of Management:

Subcategories like "All/Component" and "All/Saleable" allow for more specific configuration and management. These subcategories can have their own specific rules and settings that apply only to the products categorized under them.

In the context of an Odoo website shop, the "All" product category and its subcategories ("All/Component", "All/Saleable", etc.) impact how products are organized and displayed to customers

Hope it helps