Details of the Cardano native assets implementation are available on the developers site. The introduction notes:
Native Tokens is the name of Cardano’s Multi-Asset (MA) support feature, which enables users to transact with ada, and an unlimited number of user-defined (custom) tokens natively.
Native support offers distinct advantages for developers: there is no need to create smart contracts to handle custom tokens, for example, which removes a layer of added complexity and potential for manual errors since the ledger handles all token-related functionality.
The Native Tokens feature extends the existing accounting infrastructure defined in the ledger model (originally designed for processing ada-only transactions) to accommodate transactions using a range of assets. These assets include ada and a variety of user-defined custom token types.https://developers.cardano.org/en/development-environments/native-tokens/native-tokens/
There is also a great multi asset explainer and some worked examples.
We like the minimal (dare we say Unix like?) approach that the development team have taken. It bodes well for the future.