Understanding token standards

In this section, we will have a deeper look into ERC20 tokens and why there was a need for other token standards, such as ERC721 and ERC827.

ERC20

If you go to Ethereum wiki and have a look at the ERC20 token standards, you can see all the functions and events that you can implement. Moreover, most tokens are ERC20 compliant. You can see that the Golem network token (GNT) is only partially ERC20 compliant, but it is still a standard token; you don't exactly have to follow everything, but it is always better if you do. Among these functions, what we haven't seen before is allowance and approve. These functions can be useful in certain situations. If, for example, you have 20 MetaCoin...