# IERC20 *Interface of the ERC20 standard as defined in the EIP.* ## totalSupply ```solidity function totalSupply() external view returns (uint256) ``` *Returns the amount of tokens in existence.* ## balanceOf ```solidity function balanceOf(address account) external view returns (uint256) ``` *Returns the amount of tokens owned by `account`.* ## transfer ```solidity function transfer(address recipient, uint256 amount) external returns (bool) ``` \_Moves `amount` tokens from the caller's account to `recipient`. Returns a boolean value indicating whether the operation succeeded. Emits a {Transfer} event.\_ ## allowance ```solidity function allowance(address owner, address spender) external view returns (uint256) ``` \_Returns the remaining number of tokens that `spender` will be\ allowed to spend on behalf of `owner` through {transferFrom}. This is\ zero by default. This value changes when {approve} or {transferFrom} are called.\_ ## approve ```solidity function approve(address spender, uint256 amount) external returns (bool) ``` \_Sets `amount` as the allowance of `spender` over the caller's tokens. Returns a boolean value indicating whether the operation succeeded. IMPORTANT: Beware that changing an allowance with this method brings the risk that someone may use both the old and the new allowance by unfortunate transaction ordering. One possible solution to mitigate this race condition is to first reduce the spender's allowance to 0 and set the desired value afterwards: Emits an {Approval} event.\_ ## transferFrom ```solidity function transferFrom(address sender, address recipient, uint256 amount) external returns (bool) ``` \_Moves `amount` tokens from `sender` to `recipient` using the\ allowance mechanism. `amount` is then deducted from the caller's\ allowance. Returns a boolean value indicating whether the operation succeeded. Emits a {Transfer} event.\_ ## Transfer ```solidity event Transfer(address from, address to, uint256 value) ``` \_Emitted when `value` tokens are moved from one account (`from`) to\ another (`to`). Note that `value` may be zero.\_ ## Approval ```solidity event Approval(address owner, address spender, uint256 value) ``` *Emitted when the allowance of a `spender` for an `owner` is set by*\ *a call to {approve}. `value` is the new allowance.*