A top-level — or L1 — category on an eBay marketplace is a named grouping of similar items, such as "Collectibles", "Fashion", or "Electronics". Categories are organized into a hierarchical structure whih is conceptually similar to the directories in a file system.
Categories that contain actual listings are called "leaf" categories.
The following example illustrates a typical full path where Collectibles is the Level 1 (L1) category and Presidential is a Level 4 (L4) "leaf" category.
Collectibles > Autographs > Political > Presidential
The full name of this leaf category as it will be displayed on the eBay.com site is Collectible Presidential Autographs.
It is important that a seller place an item in the proper category as it should increase traffic to, and sales from, the listing. In eligible categories, sellers can list items in an additional, "secondary" category. However, additional fees may apply when listing items in two categories.
There are CategoryID values associated with every eBay category which are generally used by API calls to identify a category.
Categories and the category hierarchy will vary between eBay marketplace. For example, the category hierarchy and available categories on the US eBay site vary from those on the eBay Germany site. For categories that are basically the same but on different marketplaces, the CategoryID value may be the same, but the category name may vary slightly and the category name is always localized into the default language for the site. Each eBay marketplace will have unique categories that are only of regional interes or are of interest to a particular culture.
The Trading API's GetCategories call can be used to retrieve all categories for a specific eBay marketplace. This call can also be used to retrieve a subset of the category hierarchy. For example, a user may want to grab only those categories that fall under the 'Collectibles' L1 category.
Categories and/or the category hierarchy for an eBay marketplace are typically updated about once per quarter. An application could download the categories once and then periodically run the GetCategories call to determine if the CategoryVersion and/or UpdateTime values have been updated.
For more information refer to: