INHERITANCE

ERC-20 is a technical standard used for smart contracts on the Ethereum blockchain for
implementing tokens . ERC stands for Ethereum Request for Comment, and 20 is the number
that was assigned to this request. The clear majority of tokens issued on the Ethereum
blockchain are ERC-20 compliant. As of 2018-07-26, a total of 103621 of ERC-20 compatible
tokens are found on Ethereum main network, according to Etherscan.io.
ERC-20 defines a common list of rules for Ethereum tokens to follow within the larger Ethereum
ecosystem, allowing developers to accurately predict interaction between tokens. These rules
include how the tokens are transferred between addresses and how data within each token is
accessed.
Currently Ether does not conform to the ERC-20 standard. Protocols which require ERC-20
compliance for trading have created Wrapped Ether tokens as a place holder for ETH.
ERC-20 was proposed on November 19, 2015 by Fabian Vogelsteller. It defines a common list of
rules that an Ethereum token has to implement, giving developers the ability to program how new
tokens will function within the Ethereum ecosystem. The ERC-20 token standard became
popular with crowdfunding companies working on initial coin offering(ICO) cases due to the
simplicity of deployment, together with its potential for interoperability with other Ethereum token
standards.
As of July 26 2018, there were more than 103,621 ERC-20 token contracts.

Functions
The ERC-20 token has the following method-related functions:
The specific wording of the function is followed by a clarification of what it does, in [brackets]
1. totalSupply() public view returns (uint256 totalSupply) [Get the total
token supply]
2. balanceOf(address _owner) public view returns (uint256 balance) [Get
the account balance of another account with address _owner]
3. transfer(address _to, uint256 _value) public returns (bool success)
[Send _value amount of tokens to address _to]
4. transferFrom(address _from, address _to, uint256 _value) public
returns (bool success)[Send _value amount of tokens from address _from to
address _to]
5. approve(address _spender, uint256 _value) public returns (bool
success) [Allow _spender to withdraw from your account, multiple times, up to
the _valueamount. If this function is called again it overwrites the current
allowance with _value]
6. allowance(address _owner, address _spender) public view returns
(uint256 remaining) [Returns the amount which _spender is still allowed to
withdraw from _owner]

Events format:

1. Transfer(address indexed _from, address indexed _to, uint256 _value).
[Triggered when tokens are transferred.]
2. Approval(address indexed _owner, address indexed _spender, uint256
_value)[Triggered whenever approve(address _spender, uint256 _value) is
called.]