Difference between ERC20, ERC721, ERC23 and ERC223 Tokens

What is a Token? In the previous post I mentioned that the primary difference between Ethereum and any other cryptocurrency is that Ethereum is not just a currency, it’s a global computing engine. Ethereum allows creation of distributed applications where smart contracts play a central role. Another important concept within the realms of distributed apps is a token. Tokens can be thought of as a currency within an application built on top of Ethereum.