Chapter 14, Writing Token Contracts

1. Fungible (ERC20) and non-fungible (ERC721). 
2. ERC223 helps in contract-to-contract communication, especially with regard to token transfer from one contract to another. It provides guidance for the implementation of the tokenReceiver function and its call to ensure that tokens are not lost. 
3. ERC165 helps to publish the interfaces supported by a contract. If an interface is supported, all its functions will also be available for invocation. Clients can use the supportsInterface function provided by ERC165 to check whether a contract implements an interface and, if so, can consume its function.