Assets are files retrieved by the engine, including instances or services, and can be retrieved through Content protocols, such as "rbxasset" for retrieving a local file. An asset type is a type of format for content retrieved by the engine. Many asset types share a similar format. For example, the types model, decal and accessories all represent instance data.
On Roblox, assets are items that uses the ID type Asset and are primarily used across experiences. Their Content protocol is "rbxassetid". Every asset has an asset type that represents the format of its content. Asset types determine their catalog (the marketplace if it is avatar-related, the games page if it is a place, otherwise the Creator Marketplace) and their category in the catalog. All asset types have a name, which is used in some URL parameters on the website. The library catalog category IDs are used in the query string for searches with the library catalog API. Asset types are represented by the AssetType enum.