Tokens on Ethereum
Blockchain tokens existed before Ethereum.
- In some ways, the blockchain currency,Bitcoin,
may be a token itself. - There are many any token platforms were also developed on Bitcoin and other cryptocurrencies before Ethereum.
- Introduction of first token standard on Ethereum led to an explosion of tokens.
Tokens standards (ERC20)
- The first standard was launched in November-2015 by Fabian Vogelsteller as an Ethereum Request for Comments (ERC).
it had been automatically assigned Github issue number 20, giving rise to the name "ERC20 token". - The
overwhelming majority of tokens are currentlysupported the ERC20 standard. ERC20may be a standards for fungible tokens, meaning that different units of an ERC20 tokens are interchangeable andhaven't any unique properties. - The ERC20 standard defines
a standard interface for contracts implementing a token,such any compatible tokenare often accessed andutilized in an equivalent way.
ERC20 Required functions and events
total Supply:Returns
balance Of:
Given an address, always returns the token balance of that address.
transfer:
Given an address and amount, transfers
transfer From:
Given a sender, recipient, and amount, transfers tokens from one account
approve:
Given a recipient address and amount, authorizes that address to execute several transfers up
allowance:
Given an owner address and a spender address, must returns the remaining amount that the spender is approved to withdraw from the owner.
Transfer:
Event depends upon a successful transfer(call to transfer or transfer From) even for zero-value transfers.
Approval:
Event logged upon a successful call to approve.